Littelfuse LLSRK-400ID is a current-limiting fuse designed for high-interrupting capacity protection in low-voltage power distribution systems. It provides a 400A current rating and a 600V AC voltage rating, engineered to safely interrupt fault currents up to 300kA. The fuse features a single-barrel, RK1 class construction with a 2.59-inch diameter and utilizes clip-style connections for secure installation. It complies with industry standards for high-performance circuit protection and is typically applied in industrial service entrance equipment, switchboards, and motor control centers.