120V rail protection in a single bidirectional device
A single bidirectional channel clamps both polarities, so one part replaces two unidirectional devices in series on a balanced line. Peak pulse power is 600W for the standard 10/1000 µs waveform, with a maximum clamping voltage of 193V at the rated peak pulse current of 3.1A. That clamping ceiling tells you the voltage the downstream circuitry must survive during a surge event.
Breakdown window and temperature range
Minimum breakdown voltage is 133V, so the device starts conducting between 133V and the standoff voltage — a 13V guard band that keeps the TVS off the rail during normal 120V operation while triggering well before the 193V clamp.