Cooper Bussmann BK-HTB-66I-R or HTB-66I Cartridge Fuse Holder. Front Hex Nut. For 6x30mm (1/4 in x 1-1/4 in) Fuses. In-Line Panel Mount BUSSMANN BK-HTB-66I-R Cartridge Fuse Holder For 6x30mm (1/4 in x 1-1/4 in) Fuses In-Line Panel Mount. Quick Connect. Front Hex Nut