8WD1007 Captains Chair Features Rotational Molded Thick Wall Plastic Seat Frame with T-Nut Mounting Inserts. Snap On and Off UV and Mildew Treated Marine Grade Vinyl Cushions with Mesh Underlay to Expel Moisture. Molded Arm Rests with Padded Cushions. 8WP21-374 12 to 18 Adjustable Pedestal with 5 Travel Fore and Aft Seat Slide. Features 9 Diameter Polished Aluminum Base Plate, 2 7/8 Thick Wall Aluminum Post. Seat Mount Swivels 360 Degrees with Locking Mechanism. Comes with Injection Molded Plastic Mounting Plate Pre-Mounted to Seat Frame. Seat Dims; Height 21, Width 17 1/2, Depth 24, Seat Depth 15.