The SDV1005S5R5C0R5YPTF is a Varistor 5.5V 22-28 40V 0402 RoHS, which is manufactured by Sunlord. This part is a disc-shaped component that utilizes metal oxide and is generally placed across a circuit in order to protect it from spikes in electrical voltage. The specific part has a 5.5V voltage rating, a 22-28 resistance range, and a 40V break-over voltage. It is also RoHS compliant, measuring just 0402 in size. The primary purpose of the Varistor is to respond to rapid electrical changes, thus providing the circuit with an extra layer of protection.