In engineering terms, ViseGrip latching mechanisms have an exceptionally high degree of mechanical advantage. Translation: they are very, very strong. But, the patented design also makes them marvelously easy to operate. The latch (either sculpted aluminum or polished stainless steel) is a beautifully smooth shape that fits the hand perfectly. The hinge includes a stainless steel hinge pin and brass bushings between moving parts for silky smooth folding action. Dahon patented technology.