This is a fixed extension post for seat replacement or installation. Manufactured with aluminum, it will withstand harsh marine environments and provide secure mounting for your boat seats. - Pedestal tubes are hard-anodized aluminum - All springs are stainless steel - Bases are bead-blasted (to close aluminum porosity) and clear-coated - Slider has gear-tooth lock mechanism; locks solidly, disengages easily - Slider rides smoothly on acetal linear bearings - Styling is clean and uncomplicated - Handles are ergonomically designed to be easy on the hands and easy to reach Warning: Product may contain materials cautioned by California Proposition 65