Adjustable Height Locking Pedestal - adjusts from 12" to 18" in height Thick walled, 2 7/8" polished anodized aluminum post, 9" diameter base with recessed mounting holes Seat spider mount with adjustment knob and locking paddle handle, 360° rotation with locking knob Standard 5 1/4" hole pattern fits virtually all marine seat brands Class AD certified per ABYC standards