Anodized Aluminum 30" Height Accepts Garelick fore & after seat slides & 360 Degrees swivel spider combinations Compatible with Garelick hardware Provides solid base of support for a variety of seat hardware 6 hole base plate Accepts Seat Slides: 20000, 20001, 21000, 21001, 75080, 75081, 75082, 75083 Accepts Spiders: 99023, 99026 2.875" diameter ribbed stanchion tube, 9 1/4" diameter 6 hole base plate Diameter: 2.875" Stanchion Tube, 9 1/4" Base Plate