Universal Metal Coupler and Insulated Draft Gear box Metal Medium (9/32") Centerset ShankThe NO.5® Kadee® Magne-Matic® Coupler features a Metal Coupler, 634 Centering Spring, insulated 232 Draft Gear Box and Lid with side and center screw holes for mounting. The NO.5® Coupler may be mounted with supplied 232 draft gear box or with manufactures cast-on coupler pockets. It is not recommended to use a metal coupler directly on a metal surface or in a metal draft gear box to avoid the possible electrical crossover or shorting that may cause damage. Use the provided insulated draft gear box or use the very strong plastic isolated 28 Coupler which has the same mounting dimensions as the NO.5® Coupler.Two pair per package