MF-R400-2-99 is a radial leaded PTC resettable fuse designed to protect low voltage power supplies and electronic loads from overcurrent conditions. It features a hold current (Ihold) of 4.0 A and a maximum voltage rating of 30 V, with an initial resistance of 0.03 O at 23°C and a post-trip resistance of 0.05 O maximum. The device exhibits a maximum time to trip of 12.7 seconds at 23°C with a tripped power dissipation of 2.50 W typical. Constructed with cured, flame-retardant epoxy polymer insulation meeting UL 94V-0 requirements, the fuse is RoHS compliant and halogen-free. It is commonly used in computers, peripherals, and general electronics applications where reliable overcurrent protection and automatic reset capability are essential.