1500W peak pulse power in a bidirectional axial Zener
The single bidirectional channel covers both polarities, so you protect a bipolar signal or AC-coupled line with one device instead of two back-to-back unidirectional parts.
Breakdown, standoff, and clamping — the protection window
The minimum breakdown voltage is 15.2V, the reverse standoff is 12.2V, and the maximum clamping voltage at 67.3A peak pulse current is 22.3V. The 12.2V standoff lets the part sit on a 12V nominal rail without conducting in normal operation; the 22.3V clamp keeps the transient below the downstream device's absolute maximum rating.
Microchip lists the 1N6147A as Active. The axial through-hole package (B, Axial) is a standard, rework-friendly form factor that survives multiple soldering cycles.