Down Rigger/ Crab & Shrimp Pot Swivel Base. Simply the best swivel base on the market. Never get a rigger or pot puller hung up with a push pin style base again. Delrin bearing surface insures riggers and pot pullers will always swivel, 32 position gear block with posi lock stainless components . It fits in any of Bert's track and utilizes two tension knobs to lock in into place. Bert's track has grooves that prevent movement after the swivel base is locked down and the adjustment lever is easily operated. We use Polymer bearings, top and bottom, so there is no metal to metal contact. Bert's Track not included.