Kadee 804 O Scale Medium Centerset Plastic Couplers with Plastic Gearboxes - Black

O Scale Medium Centerset Plastic Couplers with Plastic Gearboxes - Black Original Style Head Medium Centerset Plastic Couplers, and #850 O Scale centering spring and comes complete with Plastic Gearboxes and lids. The #804 Plastic Coupler may be mounted with the included #817 Plastic Gearbox or #818 Metal Gearbox (sold seperately), #819 Extended Metal Gearbox (sold seperately). 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.