Scotty Rail Mount Adapter 242Fits 7/8 & 1 diameter round rail, and 1 square railFor all Scotty post mount rod holdersWorks in conjunction with No. 241 Side / Deck Mount (not included)Includes stainless steel fastenersWhen using the 242 with a 1 square rail, substitute 1/4 20 x 2 round head SS machine screws (not included)WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov