Amazon.com : TEPU Boat Seat Base 7" x 7" Aluminum Alloy Material 3/4" Pin Socket, Heavy Duty Boat Seat Pedestals, Base Corrosion Resistant, High Durability, Easy Installation, Suitable for Most Boat Seats :
Springfield Marine Boat Seat Base 3300750-1 | Plug-In 2 3/8 Inch Satin
Stainless Steel Pin Post Seat Base - T-H Marine Supplies
Attwood Swivl-Eze Lock'N-Pin Aluminum Boat Seat Pedestal Mount - 7-Inch x 7-Inch Base, 3/4-Inch - Walmart.com
Springfield Taper-Lock Boat Seat Pedestal Base 9"
Attwood 9 in D-Shaped 2-3/8 Seat Pedestal Base - Swivl-Eze | iBoats