Metallics JSPMB99 Screw 1/4-20 x 1/2 PN SL MS BR (Jar 100)

A 1/4-20 brass machine screw works where the enclosure or lug is already tapped 1/4-20, which is common on larger ground bars and equipment enclosures. Note that the usual green grounding screw in a standard outlet box is 10-32, not 1/4-20, so the JSPMB99 is the wrong thread for that hole. Check the tap in your box or bar before ordering.

Brass. The JSPMB99 is a brass machine screw (the BR in the description), which is why electricians reach for it in grounding and bonding work and in boxes where a plated steel screw would rust. Brass holds up in damp interior and weather-exposed enclosures better than plain steel, and it stays non-magnetic.

At 1/2 inch of overall screw length under the pan head, the JSPMB99 is sized for thin-wall work: sheet metal enclosures, cover plates, bus bar and lug connections where the material plus any washer is well under half an inch. If you are stacking a thick lug, a washer and a nut, you will run out of thread and need a longer 1/4-20.

The JSPMB99 uses a slotted drive, which is the traditional choice for electrical terminal and grounding screws because a flat blade from a standard electrician's screwdriver seats in it and you can drive it one-handed inside a box. A slot takes less torque than a Phillips or hex before it cams out, so for high-torque assembly work pick a different drive style.