More correctly called a "lamp burner" or "socket assembly," consists of a mounting plate, fixture whip, and socket, usually from an ERS fixture.
Lampcap from a first-generation ETC SourceFour.
Lampcap from a late 1960's radial Capitol Stage Lighting ERS with medium prefocus socket.
Lampcap from a first-generation ETC SourceFour.
Lampcap from a late 1960's radial Capitol Stage Lighting ERS with medium prefocus socket.