Metallics JDS153SS 8 x 3/4 in. 1/4 Indented Hex Head Slotted Sharp Point Tapping Screws - 18-8 Stainless - Each

Either one. The JDS153SS has an indented hex head with a slot cut across it, so a 1/4 inch nut driver or a flat blade both work. The hex measures 0.244 to 0.25 inch across the flats and 0.272 across the corners, and the slot is 0.045 to 0.054 inch wide by 0.052 to 0.066 inch deep. In a panel or box where you can get a driver square on it, the hex gives you more torque without cam-out; the slot is there for tight spots where only a blade fits.

The JDS153SS is a Type A tapping screw with a gimlet (sharp) point, which is the point style meant to start in thin sheet metal and sheet metal studs with a small pilot. It is not a self-drilling screw, so it will not cut its own hole through heavier gauge material. At 15 threads per inch the thread is coarse, which is what you want in sheet stock and soft substrates rather than thick plate.

Watch for galvanic corrosion. These screws are 18-8 stainless, and Metallics notes that fastening stainless parts to aluminum or steel can set up a galvanic couple in some environments. Outdoors, in coastal air, or in wet locations that means the aluminum or steel around the screw corrodes first. Dry indoor enclosures are generally fine. If the assembly is exposed, isolate the joint or match the fastener material to the substrate instead.

Yes, the head carries an integral washer face measuring 0.322 to 0.348 inch outside diameter and 0.019 to 0.031 inch thick. That spreads the clamp load over sheet metal so the head does not pull through a thin panel, and it means you do not have to stock separate washers for the run.

They ship in a jar, with a minimum order of 100 count. Total packed weight is 0.46 lbs. That jar format holds up better than a bag in a van drawer or on a service cart.

The JDS153SS is flagged compliant for both ARRA and Buy American, though country of origin is listed as China. On a federally funded project, confirm which clause your contract actually invokes, since the two flags and the origin need to line up with the specific spec language on your submittal.

Head and drive dimensions follow ASME B18.6.3-2010, and the thread conforms to ASME B18.6.4. Hardness runs Rockwell C28-38. Those are the numbers to put on a submittal when a spec calls for standard tapping screws rather than a proprietary fastener.

Overall screw length is 3/4 inch under a head that stands 0.096 to 0.11 inch tall, so you get close to the full 3/4 inch of thread into the material. The low head profile matters when a cover plate or another panel has to sit over the fastener without interference.