Metallics JFWP36 10 x 4 in. Flat Head Phillips Wood Screws - Steel Zinc - Each

Yes, that is what the flat head is for. The JFWP36 head measures 0.34 to 0.385 inch across with a head height of 0.116 inch, so it needs a countersink of that diameter to finish flush or slightly below the surface. In softwood the head will usually pull itself in without a separate countersink; in hardwood, plywood edges, or anywhere the finish matters, countersink first or the head will tear the surface instead of seating.

Keep them dry. These are steel with a zinc finish, which handles indoor humidity and incidental moisture but is not a marine or exterior-exposure coating, and plain zinc plating corrodes fast against the copper azole and ACQ chemistry in modern pressure treated lumber. For deck framing, treated sills, or anything weather exposed, go to a stainless or a coating rated for treated wood. Indoor blocking, strapping, equipment mounting to studs, and backboards are where the zinc screw belongs.

They ship in a jar of 100, and 100 is the order minimum, so you are buying the jar rather than loose pieces. The filled jar weighs 2.511 lbs. Metallics does offer other sizes and quantities in the JFWP line by request if 4 inch is longer than you need.

They are built to ASME B18.6.1, with threads to ASME B18.6.1-1997. That is the standard governing wood screw head, thread, and recess dimensions, which is why the head width, head height, and Phillips recess all fall in published tolerance bands. If your submittal asks for a domestic-content fastener, note that the JFWP36 is not Buy American compliant and not ARRA compliant, with multiple countries of origin.

The JFWP36 has a tapered point, which is a traditional wood screw geometry: it needs a pilot hole in hardwood and in anything near an edge or end grain, or it will split the stock. It is not a self-drilling or self-tapping fastener and it is not intended for steel studs or sheet metal. For metal framing use a self-drilling screw with a drill point instead. For solid lumber framing, blocking, and plywood where you can pilot, the tapered point with 13 TPI gives better grip in wood fiber than a fine machine thread would.

Metallics catalogs the JFWP series for the electrical, plumbing, heating and air conditioning trades. A #10 x 4 inch screw is the length you reach for when you are going through drywall and a layer of plywood or firring into a stud with real holding power, mounting panelboards, backboards, strut, or equipment hangers. Same screw, same thread standard, just sold through the trade channel instead of a lumber aisle.