Machine Screw Phil Fillister UNC 4-40 x 5/16 inch in A2 Stainless - ASME BA18.6.3
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 which the screw diver is used to tighten the fixing. They are similar to a Pan head machine screw, but with greater side height. Height to diameter ratio is larger than a cheese head. Imperial Unified Coarse thread version.