The OTC Fuel Sender Lock Ring Wrench, No. 6556, is designed for removing the 4-1/2" fuel sender lock ring on 2003-2011 Cadillac CTS, SRX and STS models. The three-prong fuel sender lock ring requires high torque to loosen and tighten, the company says. This wrench is specifically designed for this service, and the 3/8" square drive is centered for even and full application of torque. This tool is covered by a lifetime warranty.