55914-S2

This is a 1/4" diameter self-tapping screw that is 3/4" long overall, and .53" under the head.  With the S2 suffix it should have a black phosphate finish.  Fastenal lists it but doesn't have it in stock, saying "Please contact your local Fastenal store about alternative items for this product or return to Sheet Metal Screws for similar items."  But Dixieland Distributors say they have it.