Standard Short Centreset Shank PlasticThis industry leading coupler features Original Style Head Short Centerset Plastic 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.One pair per packageSimple Drop in DesignTrouble Free OperationCompatible with All Kadee® O-Scale CouplersWorld-Renowned Quality & PerformanceThey just Last & Last & Last...Package Includes:(2) Each 806 Original Style Plastic Couplers - Short Centerset Shank(2) Each Short Plastic Gearboxes & lids ( 806 type)(3) Each 850 O Scale Centering Springs