The DANCO 4-Piece Repair Kit for Moen Faucets helps restore a leaky faucet. This kit is ideal for single-handle faucets and contains the parts needed to repair 1 Moen brass cartridge. O-rings are one of the simplest, yet most engineered, precise, and useful seal designs ever developed. They are available in various metric and inch standard sizes. Sizes are specified by the inside diameter and the cross section diameter (thickness). These DANCO O-Rings will help repair your leaky Moen single handle faucet. Faucets usually have one or more O-rings to prevent water from leaking out around the spout. Replacing worn-out O-rings is an inexpensive alternative to replacing the entire faucet fixture and this cartridge repair kit is sure to fix your leaky faucet needs.