The H.H. Fluorescent 1-421 is a versatile, unshunted lampholder designed for linear fluorescent or LED tubular lamps. It is primarily used with T8, T10, and T12 lamps featuring a G13 medium bi-pin base. The H.H. Fluorescnet 1-421 is often categorized as a "plunger" or "compressible" style socket, typically used in pairs with a stationary socket (LH0350) to hold the lamp in place via spring tension. It is similar or equal to the Leviton: 13570 and DM Technology: DM38-32 or 85532