Harken swivel bases are ideal when leads must rotate to face the trimmer. Ball bearing swivel bases feature dual rows of Delrin® ball bearings that swivel freely even under high loads. Bases include stand-up springs and a U-Adaptor to accept a variety of appropriate blocks. The H-241 is a simple swivel base for main and jib sheets on very small boats or for control lines on boats of all sizes. A 365 Standard Carbo Cam Cleat is included. Installation requires hole spacing of 26mm and 5RH fasteners (not supplied).