Covers the existing rough opening on older Dometic and Atwood 6-gal. water heaters. This door allows you to replace your older Atwood water heater with a new Dometic WH-6G Series water heater. The new water heaters have a square face plate, so the conversion kit is needed to cover the sides of the old rectangular opening. Nominal Dimensions for both parts  18 ½”w x 15”