Metallics FMP835M Screws 6-32 x 2 FH PH MS St-Zn (5000 pcs)

That is exactly what the extra length is for. A standard device screw is about 1/2 to 3/4 inch; at 2 inches the FMP835M gives you roughly an inch and a half of extra reach to pick up the 6-32 threads in the box or mud ring after an extension ring, thick plaster, tile, or stacked rings have pushed the device forward. If the screw bottoms out before the device seats, step down in length rather than forcing it.

The FMP835M is steel with a zinc plating, which is a dry-location and general interior finish. Zinc plate gives light corrosion resistance for indoor boxes and panel work, but for wet, damp, or exterior locations, or anywhere exposed to chlorides, specify stainless rather than zinc plated steel.

Flat head screws are countersunk, so the head sits flush with the surface it draws into. On a 6-32 flat head like the FMP835M that matters when the screw passes through a countersunk plate, bracket, or fixture pan and nothing can stand proud of the face. If the hole you are driving into is not countersunk, a round or pan head seats better because it bears on the surface instead of trying to wedge into a straight hole.

No. The FMP835M is a machine screw, meaning it has a uniform straight thread meant to engage an existing tapped hole or a nut. It will not cut its own thread in sheet steel the way a self-tapping or sheet metal screw does. Use it where the 6-32 threads are already there, such as box ears, device yokes, mud rings, and fixture brackets.

FMP835M is a bulk pack of 5,000 pieces of the 6-32 x 2 inch flat head Phillips screw. That is a stocking quantity for an electrical contractor's shop or an MRO crib, not a per-job handful, so plan on it as shelf stock across many jobs.