The #156 Scale All Metal Self-Centering Whisker Coupler features a Scale Metal Coupler (a smaller head coupler which is more to scale and is patterned after the type 'E couplers) & Metal Whisker Centering Spring, insulated Draft Gear Box and Lid. The #156 Coupler may be mounted with the supplied #242 draft gear box, other Kadee HO-Scale draft gear box shown below or with the manufactures cast-on coupler pockets. The coupler will couple and uncouple with other Kadee HO and HOn3 couplers. The coupler has the same shank length as the #26, 36 or 46 coupler which will allow the modeler to remove the existing #26, 36 or 46 coupler and replace with the new smaller coupler. The #156 coupler is made of the same metal as the #46 for strength and rigidity. 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. The #156 package contains two pair couplers, two pair of the #242 gearboxes, and instructions.