Description: Precise Design: in one Set bike trailer coupler has flat Coupler, washer, & locking pin, provides the criticals connection from your trailer to your bicycle to carry cargo when riding . Perfect Fit:Bike Trailer Coupler is designed for a wide range of Bicycle Carriers, Trailer Sizes, Models, & Style, allows you enjoying your riding with bringing your child or other items that the bicycle can't hold . Easy To Install:Bike Trailer Coupler attachment can easily to install, you need to do is fix them with a screw on bicycle, and insert the trailer attachment. Heavy Duty Quality: The bike trailer hitch coupler attachment made of steel,strong and durable, hard to damage for long time use . Functional Tool: Perfect for pulling the trailer,riding your child around,pulling the pets and towing the goods! Specification: Material:SteelSize: Hole Dia 12mmColor:Black Package Includes: 1set Bike Trailer Coupler Hitch Attachment Note: 1.Please allow 1-3 cm error due to manual measurement. pls make sure you do not mind before you bid.2.Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!