The Hirose GT21-1S-R is a retainer — a secondary locking component — for the GT21 series of wire-to-board connectors. It is not a housing or a terminal; its job is to lock the crimped terminals into the GT21 housing after they are inserted, preventing back-out under vibration or thermal cycling. The body is molded from Polybutylene Terephthalate (PBT), a material chosen for its dimensional stability and resistance to automotive fluids. The gray color is standard for this retainer variant, making it visually distinct from the housing during assembly.
Housing Compatibility and Assembly Note
This retainer is designed for use with GT21 series housings. It snaps into the housing after the crimp terminals are fully seated, providing a positive lock that meets the vibration and thermal-shock requirements typical of automotive and industrial harness applications. The PBT body withstands the same temperature range as the housing, so the assembly behaves as a single thermal unit. Confirm the specific GT21 housing part number — the retainer is keyed to the housing cavity count and polarity.