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 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 or 46 coupler which will allow the modeler to remove the existing 26 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 of the new coupler and two pair of the 242 gearboxes, and instructions.KadeePart KAD156