Surge-Trap® Pluggable SPD provides advanced overvoltage protection. Utilizing Mersen's patented TPMOV® design, which does not require fuses, a fuse holder or additional wiring in meeting the UL 1449 Third Edition standards thus providing substantial cost savings and reduced installation times. It also features a visual indicator, easy installation, fail-safe design, mechanical coding and remote monitoring. The Surge-Trap Pluggable SPD base is designed to be mounted on 35mm DIN-rail while plugs are easily replaceable upon failure without touching the base or the hassle of rewiring. 550 Volts, UL Plug .