The RF0318-000 with PTC resettable fuse 40A 30V T/R is a circuit protection device made by Littelfuse. The PTC (positive temperature coefficient) resettable fuse acts as a secondary protection element by allowing an overcurrent to pass, but then shutting off the current and resetting in the event of an overcurrent or overvoltage surge. The fuse is rated for 40A of 30V of continuous current and can reset itself up to 20 times over the course of its life span. This makes it ideal for automotive, telecom, LED lighting, consumer electronics, office equipment, and computer applications. The thin, low profile design takes up very little board space, making it easy to integrate into tight locations. The long-time thermal stability of the unit ensures reliable circuit protection.