6-32 x 1-1/2 UNC Machine Screw Phil Fillister in A2 Stainless - ASME B18.6.3
            
            
	      UNC Phillips Fillister machine screws have a large cylindrical head, with a slightly convex top surface. 
Fillister head screws are the preferred head type for counterbored holes and can also be used for protecting 
a surface by raising the level by which the tool is used to tighten the fixing. They are similar 
to a Pan head machine screw, but with a greater head height. Height to diameter ratio is also larger than a 
cheese head. Imperial Unified Coarse thread version.