MF-R300-2-99 is a radial leaded PTC resettable fuse designed to protect low voltage power supplies and electronic loads from overcurrent conditions. This device features a maximum voltage rating of 30 V and a maximum current rating of 40 A, with a hold current (Ihold) of 3.0 A at 23°C and a trip current (Itrip) of 6.0 A. The fuse exhibits an initial resistance of 0.05 O at 23°C and a post-trip resistance of 0.08 O maximum, with a maximum time to trip of 10.8 seconds at 23°C and typical tripped power dissipation of 2.00 W. The device is constructed with cured, flame-retardant epoxy polymer insulation meeting UL 94V-0 requirements and is RoHS compliant and halogen-free. It is commonly used in computers, peripherals, and general electronics applications where automatic overcurrent protection and automatic recovery are required.