MRBF - Marine Rated Battery Fuse. Satisfies ABYC 7" circuit protection rule by mounting on a 3/8" battery post, battery switch or bus bar. Appropriate for DC Main, inverter, windlass and bow thruster circuit protection. Weatherproof - suitable for small open-cockpit boats and other harsh environments. Insulating cap prevents accidental shorts. Fuses sold separately.Voltage Max. Operating: 58V DC. Amperage Max. Operating: 300A. M8 (5/16" x 18) terminal stud size.