The 515-0074F is a panel-mounting Datalamp plug-in holder designed to securely retain plug-in Datalamp cartridges with or without a screw-on collar. The holder features a mounting bushing constructed from aluminum with black anodize finish, a brass mounting nut with white nickel finish, and phosphor bronze gold-plated terminals for reliable electrical connection. The device accommodates various cartridge types and lens shapes, with front and back panel projections ranging from 7/32" to 7/8" depending on the lens configuration and collar option. This holder serves as a heat sink for incandescent Datalamps and is recommended for use with neon or long-life low-powered incandescent cartridges on metal panels, with a maximum panel thickness of 5/32".