Crouzet GN 84137120 — a high-quality 50A single-phase solid state relay (SSR).

A panel-mount solid state relay with 4–32 VDC control input and 48–660 VAC / 50A load switching, featuring zero-crossing triggering, an integrated IP20 touch-safe cover, and back-to-back SCR output for long-term reliability.
Very commonly used in industrial heating control, motor control, and automation