The GM400 Gunwale Mount is constructed of tough, glass reinforced nylon. The universal mount includes a secure locking mechanism to hold accessories fast. The GM400 is a moderately priced, extremely versatile mount that can accept the majority of our boating accessories and inserts.The GM400 is NOT compatible with the UM6080 Universal Mount used for downriggers. The products will not lock into the GM400 mount and requires a GM650 Stainless Steel Mount instead.Please check related products for compatibility.IMPORTANT: If you are installing on an aluminum boat, you must use theG410 Isolation Gasketsto provide separation between the dis-similar metals.4X (-20 by 2 long) 316 stainless steel screws, washers, self-locking nuts and a mounting template are included.WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov