30 Series Coupler Short (1/4'') CentresetHO Scale 30-Series Plastic Couplers with Gearboxes - Short (1/4") Centerset ShankThis 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 33 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 143 Whisker® Metal Coupler mounted in a 252 Snap-together Gearbox is equivalent to the 33 Coupler. The Whisker® Coupler mounted in a 252 Snap-together Gear box makes for simple and easy assembly. Other Whisker® Coupler 33 equivalent options include 153 Whisker® "Scale" Metal Coupler when mounted a 252 Snap-together Gearbox.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.Package Includes:(2) Pair 33 Plastic Shank Couplers - Short Centerset 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 Springs 33 Plastic Coupler Features:Material - Metal Knuckle, Plastic Coupler ShankShank Length - Short (1/4") (center hole to back of coupler head)Coupler Offset - CentersetKnuckle Spring - 622Centering System - Standard ShankCentering Spring - 621 Torsion Centering SpringHead - Standard HeadWorks With - 233 draft gearboxes 233 Plastic Draft Gearboxes & Lids Features:Material - Insulated PlasticDimensions - 3/8"L x 5/16"W x 9/64"HWorks With - NO.5®, 58, 20-Series Couplers 33 in a 233 monted on top. Mounting Specifications:Mounting Height - 1/2"Centerline - 25/64"Trip Pin Height - 1/32"Center Hole - 2-56 Insulated Screws are the most commonly used. (Screw length will vary) 33 in a 233 monted on bottom. Mounting Specifications:Mounting Height - 29/64"Centerline - 25/64"Trip Pin Height - 1/32"Center Hole - 2-56 Insulated Screws are the most commonly used. (Screw length will vary)