Littelfuse has marked the 1.5KE16ARL4G as Obsolete. If you are qualifying a new BOM position, look at current-production 1.5KE series parts with similar breakdown and clamping specs, but expect a board spin: the DO-201AD axial footprint is common, but the electrical window (15.2V min breakdown, 22.5V max clamp) must match your protected rail.
1.5kW peak pulse — what it protects
That 67A peak pulse current at the 22.5V clamping voltage means it can absorb a substantial surge — think a 24V DC bus hit by an inductive load dump or a lightning-induced transient on a long cable run. The 13.6V reverse standoff tells you the continuous DC rail it protects: anything up to 13.6V stays below the leakage threshold. Above that, the device starts conducting and clamps the transient to 22.5V max.
Through-hole DO-201AD — legacy board fit
The DO-201AD axial package is a through-hole form factor — hand-solderable, easy to replace in rework, and common on older or high-reliability boards where a surface-mount TVS might not survive the same surge energy. If your board already has a DO-201AD footprint, this part drops in without a layout change.