HO Scale 30-Series Plastic Couplers with Gearboxes - Long (25/64") Underset ShankTwo pair per packagePackage Includes:(2) Pair 31 Plastic Shank Couplers - Long Underset Shank(2) Pair 621 Torsion Centering Spring(2) Pair 233 Gearboxes & Lids(2) Pair 210 Washers(2) Pair 256 - 2-56 Screws(2) 622 Knuckle SpringsThis industry leading coupler features plastic standard coupler with metal knuckle, and 621 torsion centering spring and comes complete with 233 insulated draft gearbox and lid. The 31 Magne-Matic® Metal Coupler is designed mostly for body mounting with limited space either above or below the mounting platform, with or without Draft Gear Box Lid and with Draft Gearbox Lid either on top or bottom.Note: The 30-Series Torsion Spring can be mounted either below or above the coupler shank, but must always be mounted between the Coupler Spring Lid and Draft Gearbox.The 141 Whisker® Metal Coupler mounted in a 252 Snap-together Gearbox is equivalent to the 31 Coupler. The Whisker® Coupler mounted in a 252 Snap-together Gear box makes for simple and easy assembly.