What the P6KE68CARL protects and how it clamps
It offers a single bidirectional channel rated for 600 W peak pulse power (8/20 µs waveform), with a reverse standoff voltage of 58 V, a minimum breakdown voltage of 64.6 V, and a maximum clamping voltage of 121 V at 33 A (8/20 µs waveform).
The 600 W rating is the device's peak pulse power dissipation capability for an 8/20 µs waveform, which translates to a 33 A peak pulse current. This part clamps at 121 V maximum, so a 58 V nominal rail sees the transient clipped well before it reaches destructive levels.
Through-hole DO-15 — mounting and reflow considerations
The DO-15 axial package is a through-hole form factor intended for wave soldering or hand-solder assembly. It is not a surface-mount part, so it does not have an MSL rating for reflow.