Metallics DS185M 10 x 2 in. 5/16 Indented Hex Head Slotted Sharp Point Tapping Screws - Steel Zinc - Each

The DS185M is a Type A tapping screw with a gimlet (sharp) point, so it starts in thin sheet metal, and in a punched or drilled pilot hole it forms its own thread as it drives. Type A is a sheet metal screw, not a self-drilling screw, so it will not cut its own hole through heavier gauge material. With 12 threads per inch and a 2 inch length it is built for sheet metal, duct, and strut-type work rather than structural steel.

Both are flagged compliant on the DS185M, which matters on federally funded work where procurement rules apply. Country of origin is listed as multiple, so if your specification requires a single named country of manufacture on the submittal, confirm origin against the lot you receive.

Dimensions are to ASME B18.6.3-2010 and the thread conforms to ASME B18.6.4. Hardness is Rockwell C28-38 and minimum torsional strength is 48 lb-in, which are the two values a reviewer usually wants to see on a tapping screw submittal. Note that dimensions for #9 diameter are independent of ASME B18.6.4.

They ship in a box of 1000. Order minimum is 1000 pieces, so this is a bulk fastener for stocking a truck or a shop crib rather than a small count-pack. The full box runs 12 lbs.

The head is an indented hex with an integral washer face, so no separate washer is needed. Washer outside diameter is 0.384 to 0.414 inch and washer thickness 0.019 to 0.031 inch, which gives you bearing surface over a punched hole without crushing light gauge sheet. Head height is 0.105 to 0.12 inch.

Zinc plating over steel gives moderate corrosion resistance, which suits indoor electrical, plumbing, and HVAC work, including mechanical rooms. It is not a stainless screw, so for sustained outdoor exposure, washdown areas, or coastal environments a stainless fastener is the better call. Core material is AISI 1016 to 1024 steel.

Minimum torsional strength is 48 lb-in, which is the point where the screw will twist off. Most cordless impacts put out far more than that, so run a clutched driver or dial the impact well back and stop as soon as the washer face seats. Heat-treated to Rockwell C28-38, the threads form well in sheet metal but the #10 shank will shear if you keep driving after it bottoms.

It is aimed at electrical, plumbing, heating and air conditioning work. In practice that is boxes, straps, hangers, panels, and duct fittings into sheet metal. At 2 inches long with a #10 diameter it covers the deeper cases where you are reaching through insulation, a spacer, or stacked sheet to catch the base material.