This water meter lid has two diameters: 20-1/2" (inner diameter) and 23" (outside diameter); and covers a 12-1/2" x 5/8" opening (please see the specific dimensions in the specification sheet). PlumbersStock is committed to offering you even hard-to-find parts and accessories just like this water meter lid at an affordable price, aiming to provide solutions to your residential and commercial plumbing needs.