Wise Adjustable Pedestal, #8WP21-18S: * Smooth, thick-wall anodized aluminum construction * Polished metal surfaces * Seat mount spider adjusts from 12" to 18" * 2-7/8" diameter pipe * Locking seat mount * 360-degree swivel * 9" diameter base * Wise pedestal meets all ABYC safety standards * Warranty: Manufacturer will replace the boat seat pedestal if the frame is found defective within three years * Wise adjustable pedestal model #8WP21-18S