Micro Captive Bearing Traveler Cars are machined from solid aluminum, are lightweight, strong, and have smooth running Delrin captive ball bearings. Low pivot point on the shackle makes for a short lever arm and allows it to handle non-vertical loads. Use for mainsheet cars, jib sheet cars, vangs on dinghies, controls on small keelboats Safe working load: 310 lb; breaking load: 1500 lb Roll on/roll off track - no spilled bearings Open top return race reduces weight and exposes balls for rinsing