Stanchion tube, 9.25" diameter 6 hole base plate. Provides solid base of support for a variety of seat hardware. Anodized protective finish. Mounts Garelick fore and aft seat slides and 360° swivel spider combinations. Accepts seat slides: 22000, 75080, 75081, 75082 and 75083. Swivel spiders: 99023, and 99036.