Mersen GPM Panel Mount Fuse Holders are in sizes to accommodate 5x20 mm, 1/4"x1-1/4", Class CC and Midget (1-1/2"x13/32") fuses. All 30A holders have glass-filled polyester insulators for extra dependability and trouble-free installation. Patented design allows same body to accept screw or bayonet knob. Flange design allows front or rear mounting. The 10A and 15A holders are for front mounting only.