The Thule AcuTight knob features a built-in torque limiter that "clicks" when the correct fastening force is reached. The controlled torque applied to the bike frame enhances protection for sensitive bike frames. It has ergonomic soft grips and can be locked with the Thule One-Key System. The Thule AcuTight knob is compatible with all Thule rear-mounted bike racks with frame holders. A lock is not included in the package.