The UnoLiner D121 Pull Clamp is a pull clamp without hinge. Thanks to its self-locking feature, it does not need to be screwed onto the vehicle bodywork panel. This pull clamp is forged from high strength steel and features interchangeable hardened steel knurled jaws. The usual connecting hinge between the two shells is now a forged and machine turned ring, so no hinge is needed. The self-locking mechanism, a trapezoid cone and a threaded pin with spring, is held constantly in the centre of the two clamp shells, which keeps the spring securely in place. The company offers many additional types of clamps for the UnoLiner system.