Reliance KOS-300 is a high-current Edison-style fuse rated for 300 A and 600 V AC, designed for single-use protection in demanding electrical circuits. The part number KOS-300 identifies this specific fuse, and retailers describe it as a one-time fuse with a ferrule-style terminal construction. Origin is listed as China and the product is currently discontinued in major catalogs, reflecting its status as legacy inventory. The KOS-300 sits in the Edison/KOS family of fuses used in industrial power-distribution gear where a nonresettable, high-current fuse is required.
