Garelick Standard Series Seat Slide and Swivel 75083SFeatures: Provides smooth fore and aft travel and 360 seat rotation; Adds comfort and stability for any swivel boat seat; Mounts underneath seat and on top of pedestal stanchion; Compatible with any 2 7/8"(7cm) diameter tube; Convenient handles provide solid locking at any position; Meets ABYC-H31, Type A Standards & Garelick performance standards; Anodized aluminum for added protection from saltwater corrosion and weathering; Includes retaining hardware (99300) to prevent inadvertent detachment; 7" (18cm) Fore and Aft Travel 8.5" W x 13" L (22cm x 33cm) Required on Roto molded Seat Models (Includes 75081 & 99023); Adds 1 5/8" (4cm) to height. Hole Pattern: 5" x 12" (13x30cm); Assembly & Installation Instructions