Almost indestructible ABS Nylon Base Mount w/Stainless Steel Hardware……$14.00
Can be mounted on your boat in two different ways.Bolted on (if you can get
underneath your deck) or with Lag Screws. Lag screws included. Install
multiple bases on your boat to have multiple locations for your risers.
Base measures 1 3/4 in. tall and 3 1/2 in. diameter with 4 holes 1 3/4 in. apart.