Cutout is 3-3/4 inch height x 6 inch width & overall dimensions measure 5-5/16 inch height x 7-9/16 inch width x 2-1/2 inch depth. Use with either 1-1/4 inch Or 1-3/8 inch water fill hose. Includes plastic check valve with 1/2 inch MPT. Used For RV fresh water systems.