The Bird B Gone Railing Mount is an optional base that can be used to secure the Bird B Gone Repeller 360 and all sizes of the Bird Spider 360 to boat rails, pole fences, and other railing areas. The Bird B Gone Railing Mount easily secures to railing sizes up to 1 7/8” thick and can be easily removed and stowed while sailing or cruising. Simply tighten the screw until secure.