TUF-TITE 20″ Riser Lid Green, Domed lid seals to the riser with molded-in lid gasket to assure a watertight seal every time. The lid is secured with eight stainless steel screws and a horizontal screw to assure safety. This is a strong lid that is very attractive. 20-RISL-GREENStainless Steel Screws Included Molded-in Gasket – no more fighting with O-rings