Metallics TEKDHH75M 10 x 1 in. 5/16 High Hat Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - Steel Zinc - Each

No separate washer is needed. The TEKDHH75M uses a hex "high hat" washer head with a washer outside diameter of 0.364 to 0.414 inch formed as part of the screw. That bearing surface spreads load over the hole and keeps the head from pulling through strap, clip, or thin plate. Note it is a plain washer face, not a sealing washer, so it is not a roofing or weather-seal screw.

Both flags are marked compliant on the TEKDHH75M: Buy American Compliant and ARRA Compliant. Country of origin is listed as multiple, so if your submittal package requires a certificate tied to a specific mill or country for the lot you receive, request documentation against the shipped lot.

These ship in a bulk box of 5,000 pieces, which is also the order minimum. Box weight is listed at 38.5 lbs. It is a production-quantity fastener for crews running the same screw all day, not a small counter pack.

The TEKDHH75M is a #10 diameter, 1 inch long Type BSD self-drilling and tapping screw at 16 threads per inch, manufactured to SAE J78 - 2013. Minimum torsional strength is 61 lb-in and case hardness runs Rockwell C32-40, from AISI 1016 - 1024 steel. Those are the numbers an inspector or spec writer asks for when the drawing calls out a J78 drill screw.

The finish is zinc plating over carbon steel, which is a dry-interior or protected finish. For sustained weather exposure, roof deck, or treated lumber contact, specify a stainless or coated exterior-rated drill screw instead. There is also no bonded sealing washer on this head, so it will not weatherproof a penetration.

No pilot hole. The drill point cuts its own hole and the thread taps it in the same pass, which is the point of a Type BSD screw. Drive it with steady pressure and a slower gun speed in heavier steel, let the point cut, and do not lean off axis or the flutes load up before the thread catches.

At 1 inch overall with a #3 point sized for 0.110 to 0.175 inch panel, the drilled material consumes a small part of the length and the rest carries thread engagement, so it suits fastening clips, strap, hangers, and thin plate to structural-weight steel. Stacking two heavy members, or going through a thicker standoff, needs a longer screw in the same series.