Metallics JSS14516 Screw 1/4-20 x 5/16 SKT S-Scr Cup St (Jar 100)

The Metallics JSS14516 is a 1/4-20 x 5/16 inch socket set screw with a cup point, in steel. The 1/4-20 means a 1/4 inch diameter with 20 threads per inch, so it mates with any 1/4-20 tapped hole or coupling. Overall screw length is 5/16 inch.

Cup point is the right choice for that. The hollowed cup bites into the mating surface and digs a small seat, so it grips round shafts, rods, and tube without a pre-machined flat. The tradeoff is that it marks the part, so if you need to slide or reindex the shaft later a flat point is the better pick. The JSS14516 is the 1/4-20 x 5/16 cup point in steel.

Each jar holds 100 of the 1/4-20 x 5/16 cup point socket set screws. The jar pack is the standard way these ship, which suits a service van or a bin on a shop wall rather than a single-piece pull.

It is a socket (internal hex) drive, so it takes an Allen key or hex bit, not a screwdriver. A 1/4-20 socket set screw takes a 1/8 inch hex key. There is no head on the screw, so it seats fully below the surface of the collar or boss it threads into.

That is the application it is catalogued for. Metallics sells the JSS14516 as an electrical fastener, and 1/4-20 cup point set screws are the common size for set screw connectors, collars, and ground clamp bodies. The screw is steel, so it is a general purpose fastener, not a corrosion rated or plated-for-outdoor item.

On a headless socket set screw the 5/16 inch is the full overall length end to end, point included, because there is no head to measure from. That matters when you are checking whether the screw will bottom out in a tapped boss or protrude past the far wall of a collar.