SKU: 68757881577

Hillman 3/4 in. Diameter x 3-1/2 in. Length Grade 8 Heat-Treated Steel Hex Head Cap Screws, Coarse Thread, 20-Pack

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Description

Hillman 3/4 in. Diameter x 3-1/2 in. Length Grade 8 Heat-Treated Steel Hex Head Cap Screws, Coarse Thread, 20-PackHillman Grade 8 Hex Head Cap Screws, 3 4 in. x 3 1 2 in., 20 Pack Heavy duty Hillman hex head cap screws deliver Grade 8 strength for demanding assemblies. Made from heat treated steel with a washer face and coarse threads, theyre ideal for securing machinery, automotive, and structural components. Key Features: Grade 8 Strength: Heat treated steel provides superior tensile strength for high stress applications Coarse Thread: Ensures strong hold in

Hillman Grade 8 Hex Head Cap Screws, 3/4 in. x 3-1/2 in., 20-Pack

Heavy-duty Hillman hex head cap screws deliver Grade 8 strength for demanding assemblies. Made from heat-treated steel with a washer face and coarse threads, they’re ideal for securing machinery, automotive, and structural components.

Key Features:

  • Grade 8 Strength: Heat-treated steel provides superior tensile strength for high-stress applications
  • Coarse Thread: Ensures strong hold in tapped holes and with nuts; ideal for quick assembly
  • Washer Face Head: Built-in bearing surface under the hex head improves seating and load distribution
  • Partially Threaded Shank: Enhances shear strength where unthreaded grip is needed
  • Bulk Convenience: 20-pack boxed for shop and jobsite efficiency

Specifications Table:

Specification Details
Brand Hillman
Size 3/4 in. diameter x 3-1/2 in. length
Material Steel
Grade Grade 8
Finish Heat-treated yellow dichromate (heat treated)
Thread Type Coarse (USS)
Thread Coverage Partially threaded along shank
Head Type Hex head with washer face
Number in Package 20
Packaging Boxed
Category Hex Bolts / Hex Cap Screws
Package Dimensions (L x W x H) 6.8 in x 4.5 in x 3.3 in
Package Weight 10.9 lb

Frequently Asked Questions (FAQ):

Q: What size are these bolts?
A: Each bolt is 3/4 in. diameter by 3-1/2 in. length.

Q: What grade are they?
A: Grade 8 heat-treated steel for high strength.

Q: What thread type do they have?
A: Coarse thread (USS).

Q: Are they fully threaded?
A: No, they are partially threaded along the shank.

Q: How many come in a box?
A: 20 bolts per pack.

Industrial Strength, Polished Precision

There’s a quiet elegance in hardware that performs beautifully. These Grade 8 hex cap screws bring a muscular, architectural presence—clean hex geometry with a confident, coarse thread. Style them as exposed fasteners on reclaimed timbers or steel frames for a refined industrial moment. Consider them the jewelry of hardworking spaces—small details that make luxury feel effortless.

Secure your next project with Grade 8 confidence—add this 20-pack of Hillman hex cap screws to your cart now.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 68757881577

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4.3 ★★★★★
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I
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Iraq veteran 83
Boise, US
★★★★★ 5
Very heavy and thick
Style: 30 sqft
I purchased mini brands of sound ending and this is by far the heaviest sound deadening I've ever ordered. I'm not installed yet but I have a good feeling that is going to work exceptionally in blocking sound. If weight is a concern for you I would recommend a lighter product however if sound quality and a quiet ride is your priority this is the one for you.
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Reviewed in the United States on March 18, 2026
D
Verified Purchase
Dustin Felton
Omaha, US
★★★★★ 5
Siless Hybrid 3-in-1 - Far Exceeded my Expectations!!!
Model: SLH20025
I recently installed the Siless Hybrid 3-in-1 sound deadening mat in my vehicle, and I’m genuinely impressed. For just $80 for 25 square feet, this product delivers performance that rivals materials costing twice as much — and with far less hassle. If you're on the fence......Just buy it! You will not be disappointed. Easy to Install: Unlike traditional sound deadening products that are stiff, sharp, and temperature-sensitive, this mat is soft, flexible, and easy to work with. I cut it cleanly with regular scissors and pressed it into tight spaces using just my fingers, so if in you don't have a roller or install tool, a good pair of scissors and your hands can get the job done. With other brands like Dynamat, the aluminum layer often leaves micro cuts on your hands and tears up your fingertips, but Siless does not due the acoustic layer being on top and above the aluminum layer that holds the butyl layer. So, it's very easy on your hands. Even in cooler temperatures (around 50°F), I had no trouble applying it but it goes on better heated. If warm outside, I would leave the entire box out in the sun for at least 30 minutes when it's warm or heats it's very pliable and easy to mold. Make sure its where you want it because once applied it's not ever falling off. and it became even more pliable and easy to mold. No heat gun, no mess — just straightforward application. I installed 40–50 square feet throughout the interior, covering everything except the headliner and the flooring forward of the rear seat. The difference in cabin noise is astonishing. I can turn my radio up concert loud with gut-punching bass, and from outside the car, it sounds like a factory sound system at mid volume. I was blown away by how well it contains sound — both inside out and outside in. My exhaust is pretty aggressive and now is barely audible from inside the cabin. While driving, it almost sounds like a stock factory setup. The Siless matting actually changed the driving experience and feels refined. If you're skeptical about sound deadening gimmicks, I get it, but this is the first product I've used and when I needed more, I went Stright to the 3 in 1 Hybrid matting and purchased it again. I love researching before buying and that's very uncommon for me to do. Note: Proper installation is key, and it does take time and patience. But if installed correctly and in the right places, it works better previously used from paint-on sound deadening to Dynamat. Update Nov, 2025 After using it this in 4 separate vehicles now. I feel the Siless’s 3 in 1 Hybrid has nailed it for best budget deadener that is better than dynamat extreme in performance and installation Protip: buy a roll of 2-3” aluminum tape and tape the seams. After trimming the edges tend to very sticky between the panels. I ran a strip of aluminum tape over the seems to create a better seal and true moisture I used it on four vehicles now and have I have not been paid to review and purchased every order myself. 3 in 1 Hybrid deadener by Siless is the best all around easy to apply sound deadner period!
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Reviewed in the United States on September 29, 2025
T
Verified Purchase
Tee & Cee
Los Angeles, US
★★★★★ 5
Top quality
Model: SLH20025
This Siless Hybrid 3-in-1 sound deadening mat is easy to work with and feels high-quality. The butyl material is thick and pliable, making it simple to cut and fit into doors, floors, or panels. After installation, road noise and vibrations are noticeably reduced, and it also seems to improve the overall cabin feel. No bad smell. At 25 sq ft per roll, it’s a good value for anyone looking to dampen noise and improve car acoustics. Overall, a solid, effective option for automotive soundproofing. Used on a Fiesta ST.
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Reviewed in the United States on February 15, 2026
A
Verified Purchase
Andy
Birmingham, US
★★★★★ 5
Made a big improvement in cabin noise—highly recommend
Model: SLH20025
Siless Hybrid made a huge difference in reducing noise in the floor of my truck cabin. In some areas, there was basically just bare sheet metal between the inside and outside, so adding this really helped the truck feel more solid and noticeably quieter on the road. I used Kilmat on the doors, and honestly I wish I had used Siless Hybrid there too, but it was too late by the time I realized the difference. This material is very sticky, easy to cut, and simple to apply, which made the install pretty smooth. Just a heads-up: the tacky side gets messy and will bond to clothing really easily, so be careful during installation. Overall, I’d definitely buy it again—great product with real results.
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Reviewed in the United States on December 2, 2025
A
Verified Purchase
AmazinFrank
San Leandro, US
★★★★★ 5
Very good product at a fair price
Model: SLH20025
Very good sound deadener and heat shield, it is a bit sticky to work with, but easy to shape and cut
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 19, 2026

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