Keystone Electronics Corp. TR5 / BK-EFF Fuse Holder, Sturdi-Mount 3556

The 3556 is a Sturdi-Mount low profile subminiature fuse holder designed for Littelfuse 370 Type TR5 and Bussmann BK-EFF series fuses or equivalents, with a 0.335 inch (8.5 mm) fuse diameter and vertical fuse entry. It features a thermoplastic base rated UL 94V-0, brass tin-plated pins, and beryllium copper springs with gold plating, rated at 5 amps at 250 V AC. The holder mounts through-hole and includes a 0.200 inch (5.1 mm) mounting hole with 45-degree chamfers. Operating temperature range is not specified for this exact variant but follows the series limit of -58°F to +292°F (-50°C to +145°C).