This is something we have heard through several emails, and phone calls. It can be very confusing if you purchase a part that states it measures 12 inches, but the packaging for the stem is showing 8 inches. The measurement shown on the package is in reference to the wall thickness of the faucet. The wall thickness will not measure the same as the overall length of the stem assembly. With most brands the stem will be 4 inches longer than the wall thickness. If your Mansfield faucet has an anti siphon cap on the top. The overall length of the stem will be measured from the squared end all the way down to the opposite tip of the stem with the spring loaded piece extended. If your faucet does not have a cap on the top side, and the nut behind the handle is plastic. You would measure the stem from where the handle connects all the way down to the little screw in the rubber washer. Click Here To Go To The Mansfield Faucet Guide