Type E Short Centreset Shank MetalThis industry leading coupler features New Generation AAR Type "E" "Prototype" Head Short Centerset Metal Couplers, and 850 O Scale centering spring and comes complete with Short Plastic Gearboxes and lids. The 743 Metal Coupler may be mounted with the included Short Plastic Gearbox ( 806 type).It is not recommended to use a metal coupler directly on a metal surface or in a metal draft gearbox to avoid possible electrical crossover and shorting that may cause damage.Two pair per packageNew Generation AAR Type "E" "Prototype" Head:Simple Drop in DesignTrouble Free OperationHidden Knuckle SpringAAR Type "E" Coupler StyleCompatible with Kadee® O-Scale CouplersWorld-Renowned Quality & PerformanceThey just Last & Last & Last...Package Includes:(4) Each 743 Type "E" "Prototype" Metal Couplers - Short Centerset Shank(4) Each Short Plastic Gearboxes & lids ( 806 type)(5) Each 850 O Scale Centering Springs