4-Beam Clamp Coupling, Bores 0. It has pure metric outer diameter and length dimensions to fit in a smaller envelope than Ruland P-series beam couplings for easier interchanges with single beam couplings. Hardware is metric and tests beyond DIN 912 12. This MW-series beam coupling is machined from a single piece of stainless steel and features two sets of two spiral cuts allowing for higher torque capacity and lower windup than single beam couplings.