Simply replace one of the sterndrive mounting nuts for theft protection. Stainless steel with free-spinning collar that will turn if attacked by gripping tools. No assembly required. Fits Mercruiser®; Alpha, Bravo I-III (Incl. X & XR), Blackhawk, OMC Cobra & King Cobra, and Volvo SX & DP-S stern drives. 74019 twin drive set includes 2 locks and 1 key. Carded for pegboard or for P.O.P. merchandiser.