FKM Black Heat Resistant Quad Ring For Diesel Fuels , Rubber X Ring Seals The sealing principle of the Quad™- ring is nearly the same as the O-ring sealing. The initial sealing is achieved by the diametrical squeeze in a right angled groove. The system pressure itself creates a positive sealing force.Following are some advantages of Quad™-rings:- With Quad™-rings the standard grooves are deeper in comparison with O-ring glands. So diametrical squeeze is lower than with O