All Vari-Flo control valves feature an easy-to-use lever action handle that lets you "dial" up to six valve/filter functions: filter, backwash, waste, rinse, closed or recirculate. Complete with an integral sight glass that lets you see when the backwashing cycle is completed. Is preplumbed to fit Hayward Sand Filter Models S310, S311, S360

Centerline spacing of pipes is 6"

Inside dimension between pipes is 3-1/2"