10 Best Holo-krome Bolts 2026

⚡ Quick Verdict

📋 How We Evaluated

Evaluation focused on build quality signals like heat-treated alloy steel, dimensional control claims, and thread uniformity. Performance assessment emphasized shoulder and thread geometry for alignment, plus suitability for socket-head installations.

Value and suitability considered pack size and coverage for common SAE and metric repair workflows, using Amazon-style rating signals when available.

Made in The USA	Yes
Material	Black oxide alloy steel, Grade 12.9
Shoulder Length	4 inch
Thread Size	3/8-16

What We Found

The HOLO-KROME 08094 offers a larger 1/2-inch shoulder diameter. It has a long 4-inch shoulder length for deep alignment tasks. It uses black oxide alloy steel at Grade 12.9. The strength is rated to HRC 32-43. Unified 3A thread fit and ASME B18.3 compliance support consistent forms.

Burnished threads aim to reduce friction and improve uniformity. The 3/8-16 coarse thread helps with easier starts. This long shoulder provides more guiding surface than shorter options. That extra geometry can reduce wobble in loaded brackets or custom fixtures. It helps prevent wear in precise positioning setups.

Who It’s For

This suits fabricators working on assemblies that need long shoulder spacing. It fits mounting guards or structural linkages where the shoulder guides movement. The 25-pack is practical for small job shops. Coarse 3/8-16 threads help when drawings specify that series. I would double-check your bore diameter before ordering.

Standard	DIN 912
Drive Type	Hex drive
Thread Specification	M4-0.7 (course)
Length	25 mm

What We Found

The HOLO-KROME 76080 is a metric socket cap screw. It focuses on reliable clamping and easy tool access. It uses DIN 912 geometry with a hex drive. The M4-0.7 thread has a 25mm length. It uses black oxide on class 12.9 alloy steel.

Heat-treated alloy strength and precision threads are key features. These threads aim for smooth engagement and uniform torque. The metric coarse thread supports easy assembly in general mechanical builds. A 100-pack offers better value for ongoing production or electronics enclosures.

Made in the USA manufacturing ensures high dimensional control for device assemblies.

Who It’s For

This screw is for metric builds needing consistent M4 cap screws. It works for enclosures, brackets, and machine covers. The DIN 912 hex drive works with standard tools for quick service. The 100-pack is great for workshops that need spares. It also works well for hobby teams needing bulk quantities.

ASTM Standard	ASTM A574
Thread Size	1/2-13 UNRC (course)
Length	1-1/2 inch
Finish	Black oxide

What We Found

The HOLO-KROME 72230 socket cap screw uses SAE 1/2-13 coarse threading. It complies with ASTM A574 standards. It features a black oxide finish on heat-treated alloy steel. This supports high strength and durability. The listing highlights Unified thread fit and burnished precision threads. It also includes HOLO-Code traceability.

At 1-1/2 inches long, it works for deep clamping. The hex drive supports consistent tightening with standard tools. Coarse threads often tolerate minor misalignment better than fine threads. This product targets spec-driven builds that require documented standards.

Who It’s For

This fits manufacturers who need larger SAE socket-head hardware. It suits structural brackets and machine covers. It works well for clamping through thick material stacks. The 50-pack is a practical size for service technicians. It is most valuable when your specs call for A574 and UNRC coarse threads.

Standard	DIN 912
Thread Specification	M8-1.25 (course)
Length	50 mm
Finish	Black oxide

What We Found

The HOLO-KROME 76260 is a metric socket cap screw. It uses DIN 912 geometry with M8-1.25 threading. It has a 50mm length. The construction uses black oxide and Class 12.9 alloy steel. The listing highlights stronger-than-conventional screws and precision threads. These burnished surfaces target consistent engagement.

It also features Made in the USA manufacturing for dimensional control. The M8 diameter and 50mm length support deeper clamping. It uses a standard hex drive for controlled torque. This is helpful when metric threads reduce the risk of cross-starting.

Who It’s For

This screw suits metric assemblies that need longer clamp spans. It fits machine frames, mounting rails, and structural covers. The 100-pack works well for maintenance teams. Coarse M8-1.25 threads help with assembly tolerance. I would recommend checking your material thickness before ordering.

Made in The USA	Yes
Material	Black oxide alloy steel, Grade 12.9
Shoulder Diameter	3/8 inch
Thread Size	5/16-18

What We Found

The HOLO-KROME 08046 shoulder bolt works well for precision alignment. It features a 3/8-inch shoulder diameter and a 1-1/4-inch shoulder length. The black oxide alloy steel uses Grade 12.9 construction. Heat treatment reaches HRC 32-43 for extra strength. It follows Unified 3A thread fit and ASME B18.3 standards.

These burnished threads help reduce variability during assembly. The 5/16-18 coarse thread matches the common SAE series. Since it is made in the USA, you can expect high dimensional control. This matters when locating shoulder sections in machined housings. It prioritizes thread accuracy and shoulder consistency for repeatable fits.

Who It’s For

This bolt is for builders using shoulder length as a spacer or a pivot. It works for equipment repairs where shoulder diameter affects part mating. This includes light industrial brackets or machine guards. The 25-pack is good for prototyping and targeted repairs. Coarse 5/16-18 threads work well for existing installations.

I would suggest matching the mating bore to these ASME standards.

Made in The USA	Yes
Material	Black oxide alloy steel, Grade 12.9
Shoulder Length	2 inch
Thread Size	1/4-20

What We Found

The HOLO-KROME 08032 shoulder bolt pairs a 5/16-inch diameter with a 2-inch length. It targets mid-depth alignment needs. It uses black oxide alloy steel at Grade 12.9. The material is heat treated to HRC 32-43. It follows Unified 3A thread fit and ASME B18.3 standards.

These aim for consistent dimensions and burnished smoothness. The 1/4-20 coarse thread is suited for specific SAE applications. Being made in the USA, it emphasizes dimensional control. This helps the shoulder seat consistently in machined parts. It balances shoulder length with a smaller diameter for compact assemblies.

Who It’s For

This bolt suits compact machinery repairs. It works when part alignment relies on a shoulder rather than a threaded shank. It fits brackets, small hinges, and positioning fixtures. The 25-pack is good for repair kits. I would recommend verifying thread compatibility with your mating parts first.

ASTM Standard	ASTM A574
Thread Size	#6-32 (course)
Length	1/4 inch
Finish	Black oxide

What We Found

The HOLO-KROME 72038 is a small ASTM A574 hex drive screw. It is built for precise control in a micro SAE size. It uses alloy steel with a black oxide finish. The #6-32 thread has a 1/4-inch length. It meets ASME B18.3 and ASTM A574 standards.

The 7/64-inch hex drive suits compact assemblies. The product emphasizes heat-treated strength and precision. Burnished threads help ensure uniformity and accuracy. For miniature components, consistent thread form prevents galling. This helps achieve predictable torque in repeated assemblies.

Who It’s For

This screw fits small electronics enclosures and compact machine linkages. It works for precision accessories using #6-32 hardware. The 1/4-inch length matches common small mounting stacks. The 100-pack supports frequent replacement in repair workflows. It suits shops that want consistent performance for small fasteners.

Made in The USA	Yes
Material	Black oxide alloy steel, Grade 12.9
Shoulder Diameter	1/4 inch
Thread Size	#10-24

What We Found

The HOLO-KROME 08002 shoulder bolt has a 1/4-inch diameter. It features a short 0.375-inch shoulder section. It uses black oxide alloy steel at Grade 12.9. The heat treatment reaches HRC 32-43. It follows Unified 3A thread fit and ASME B18.3 standards. These ensure smooth burnished threads and uniformity.

The #10-24 coarse thread suits common small SAE needs. A shorter shoulder is useful when you need a small locating feature. Shoulder bolts can reduce shear load on threaded portions. This helps maintain alignment in compact mechanisms.

Who It’s For

This suits compact builds that need a locating shoulder with minimal protrusion. It fits small brackets and lightweight machine parts. It works for hinge-style mounting points. The 25-pack is good for small repair inventories. I would suggest confirming your bore diameter before use.

Thread Size	#5-40 (course)
Length	1/4 inch
Finish	Black oxide
Drive Type	Hex drive socket cap

What We Found

The HOLO-KROME 72028 socket cap screw serves small SAE #5-40 applications. It has a 1/4-inch length and black oxide alloy steel construction. It is made in the USA for high dimensional control. The heat-treated alloy steel provides extra strength. Precision threads offer smooth engagement and accuracy.

This helps maintain consistent torque-to-tension behavior. The hex drive design includes coarse-thread characteristics. This allows for easier assembly and better tolerance to misalignment. The 100-pack is great for keeping small hardware on hand. It reduces downtime for frequent micro-fastener replacements.

Who It’s For

This fits precision and small-scale mechanical builds using #5-40 hardware. It suits model machinery, compact mounts, and electronics fixtures. The 100-pack is great for repair technicians. Coarse #5-40 threads support easier installation during rework. I would verify the thread callout on your drawings first.

ASTM Standard	ASTM A574
Thread Size	#4-40 (course)
Length	3/8 inch
Finish	Black oxide

What We Found

The HOLO-KROME 72020 socket cap screw targets #4-40 SAE assemblies. It has a 3/8-inch length and black oxide finish. It uses ASTM A574 compliant heat-treated alloy steel. The burnished threads improve uniformity and accuracy. This ensures consistent engagement. The coarse thread series and hex drive make installation straightforward.

At this scale, thread smoothness minimizes galling. It also helps achieve predictable clamping force during repeated cycles. The 100-pack provides good value for prototyping or frequent replacement. This product fits small mechanical contexts where consistency affects component lifespan.

Who It’s For

This screw fits miniature machine builds and small brackets. It works for hobby-grade mechanical assemblies specifying #4-40. The 3/8-inch length suits moderate mounting stacks. A 100-pack supports ongoing maintenance and rapid prototyping. I would suggest verifying the tool fit since micro fasteners are unforgiving.

What to Look For Before Buying

Matching your thread size, series, and standard to the mating part is the first step. For shoulder bolts, focus on diameter and length to determine alignment. For socket cap screws, check the drive type and threading. Finally, compare the pack size to your expected repair frequency.

Check Match Thread Size and Series Exactly

Confirm diameter and thread callouts like 5/16-18 or #10-24 before you order. Check if the series is coarse or fine. This affects your assembly tolerance. Keep mating hardware standards consistent for ASTM A574 and ASME B18.3 products. Shoulder bolts also need a matching bore size.

Value Choose the Right Pack Size for Your Work Pattern

Small quantities work for one-off repairs. However, 50 or 100-packs favor recurring maintenance and production. Prototyping benefits from bulk socket cap screws. If you use the same size repeatedly, bulk value is usually better. Consider your spare needs for shoulder bolts.

Rating Use Rating Signals, Then Validate Specifications

If ratings are available, look for trends regarding thread quality and fit. If rating data is missing, rely on published standards. Look for ASTM A574, ASME B18.3, or DIN 912 compliance. Also verify heat-treatment claims like HRC 32-43. Treat missing data as a cue to double-check compatibility.

Verify Verify Geometry for Shoulder Alignment and Clamp Depth

For shoulder bolts, ensure the shoulder length provides the required guiding surface. Make sure the threaded portion supports full engagement. For socket cap screws, measure your stack thickness. You should also check the required thread engagement. Consider your environment when choosing a black oxide finish.

Frequently Asked Questions

What does “Unified 3A thread fit” mean for these Holo-Krome bolts?

Unified 3A is a thread class designed for consistent engagement. It helps make assembly more predictable. This is important for shoulder and socket cap applications. It helps reduce the risk of looseness.

Are black oxide Holo-Krome bolts corrosion resistant?

Black oxide offers limited protection compared to zinc plating. It works well for indoor workshop conditions. For humid or outdoor environments, you should consider additional protective measures or different finishes.

How do shoulder bolt dimensions affect performance?

The diameter and length determine how parts align. They also control how load transfers between the shoulder and threads. A matching bore helps the shoulder guide positioning. This reduces stress on the threads.

When should DIN 912 or ASTM A574 matter?

DIN 912 specifies the socket cap screw geometry. This ensures tool compatibility and consistent proportions. ASTM A574 relates to heat-treated alloy steel performance. These standards help you maintain compatibility with existing assemblies.

What’s the best way to avoid micro-fastener stripping?

Use the correct driver size and stay within torque limits. Start the threads by hand to prevent cross-threading. This is vital for #4-40 and #5-40 sizes. Keep mating threads clean and do not force them.

🎯 Final Verdict

The HOLO-KROME 08094 is a standout for long shoulder alignment. It pairs a 4-inch shoulder with Grade 12.9 heat-treated steel. This helps prevent wobble in real assemblies. For larger SAE sizes, the HOLO-KROME 72230 is a strong alternative. It offers ASTM A574 alignment and coarse threads.

Confirm your bore diameter and thread series before you order.