This 3/4-size coupler has an extended trip pin mounted on a narrow gauge coupler to use with light duty old time equipment. The #711 and #712 works with Kadee′s full size HO-Scale couplers. With this smaller coupler, gathering will not be as great nor can they bear the same loads as Kadee′s HO couplers. They should easily handle loads common to the pre-1900 era.