Use cam swivel bases when leads must rotate to face the trimmer. The 240 and 241 are simple swivel bases for main and jib sheets on very small boats or for control lines on boats of all sizes. Ball bearing swivel bases feature dual rows of Delrin ball bearings to ensure that they will swivel freely even under high loads. The bases include a stop that prevents the base from swiveling completely and fouling lines. Bases include stand-up springs and a U-adaptor to accept a variety of appropriate blocks. The 144 is the standard configuration with a tall arm. It is ideal for mounting in the cockpit or for use on larger keel boats and small offshore boats that use 3.00" (76 mm) plastic blocks. The low- profile 205 is used when installation is at deck level and when / smaller blocks are used. The 216 features a second cleat for lines led vertically through (the base of the swivel. It is frequently used to combine vang or backstay controls in the same swivel base that handles the mainsheet. The 402 and 403 are fitted with a double cam for use in two- speed mainsheet systems.