Springfield Marine Taper Lock Deck Base 9" Round 9in Round. It is constructed of high-strength aluminum to withstand all conditions. Use with any Taper-Lock Post (sold separately). Features of Springfield Marine Taper Lock Deck Base 9" Round Satin finish High-strength aluminum construction Below the deck mount requires a 3-1/2" hole in deck Use with any Taper-Lock Post (sold separately) 9" round base with an 8" hole pattern Package Contents: Springfield Marine Taper Lock Deck Base 9" Round Springfield Marine 1600003: Taper Lock Deck Base 9" Round 9in Round