FHM In-Line Fuse Holders Littelfuse FHM In-Line Fuse Holders provide additional or remote circuit protection and can be mounted virtually anywhere. These fuse holders feature an integrated cover that helps achieve an IP67-rating. The FHM fuse holders are available in custom and semi-custom versions and with various lead wire sizes, insulation colors, wire tinning, and wire types. These fuse holders are used in accessory or overflow circuits and small electric motors.