These screws are used to secure plates to Foxx Mount Extrusion. Price is for a single screw.
The 1/4-20 screws come in three lengths. The rule of thumb for length is, steel plates use 3/8, aluminum plates use 1/2, with the exception of the Top Plates, which use 3/4" screws.
All screws have a 5/32" Socket, for use with the allen wrench that comes with desk mounts.