The JST EHR-3 is a 3-circuit receptacle housing from the EH series, designed for inline wire-to-wire or wire-to-board connections where a compact, single-row footprint at 2.50mm pitch is called for. It accepts female crimp sockets (ordered separately — see the note on contacts) and mates with the matching EH series pin header.
Three circuits at 2.50mm pitch is a common count for small sensor feeds, switch inputs, or low-current power taps where you need three wires in a single inline connector. The single-row layout keeps the housing narrow — about 7.5mm wide across the body — which fits into tight wire bundles or behind a panel where a dual-row would be too wide.