Valterra A01-2003 BLACK Gravity Water Fill Hatch Inlet UV Stabilized Plastic & Screws RV Camper Trailer 

Gravity water inlet features a bayonet style cap, 1/2" air vent for faster fill rate and a 1 1/4" barn connection. Discharge is angled.

4 1/2" round   Fits  3 1/2" cut out

Please let me know if you have any questions.  Thank you, Babette