The MARATHON/KULKA RF400A1B is a heavy-duty reinforced fuse holder engineered for demanding industrial environments. This fuse holder is rated for up to 400 amps and 250 volts AC/DC, providing reliable protection for critical circuits. Constructed with high-quality materials including tin-plated copper fuse clips, aluminum box connectors, and a thermoset polyester insulator base, the RF400A1B ensures durability and optimal performance. It is UL Listed to UL 512, CSA Certified to C22.2 No. 39, and CE compliant to IEC 60947-1, demonstrating adherence to stringent safety standards. The holder accepts commonly used fuse sizes and is designed for easy installation with a 5/16” hex key and #1/4” fastener.