The Hirose GT21-1S-HU is a single-position housing from the GT21 series, molded in gray Polybutylene Terephthalate (PBT). It is an F-style connector housing, meaning it accepts F-type crimp terminals — not M-type. This is a housing-only part; you order the terminals separately. The matching terminal family is listed as F Terminals, so confirm your BOM includes the correct crimp contacts before you build.
The single-position cavity suits discrete wire runs where you need one circuit per housing — common in sensor leads, power taps, or signal pickoffs where a multi-position connector would over-occupy the board. The PBT body handles the typical underhood or industrial cabinet temperature range without issue. Because it is a housing, the current rating and voltage rating depend entirely on the terminal and wire you crimp into it, not on the housing itself.