A bike trailer coupler is an way to do that. This is the part that you can connect your trailer to your bike. It is called a coupler, it acts like a trailer hitch for your bike. With bike trailer attachment, the bike trailers are easy to attach to your bike while allowing you to transport your little children in safety and comfort. Features - Color: Black. - Material: Iron. - Size: 7.50 x 5.50 x 3.00cm/ 2.95 x 2.16 x 1.18 inch. - This iron hitch provides excellent durability. The solid construction, and black paint make it looks your bike when no trailer is connected. - Very easy to switch between our bikes to hook up the trailer. You can unhitch the wagon quickly and then reattach it with ease. - It was easy to attach to the rear wheel assembly by just removing one nut. A must have if you wish to easily switch the trailer between bikes. - If you want get some outdoor fun with your kids or pets, use this bike trailer hitch. - Perfect for pulling the trailer, riding your kids around, pulling the pets and towing . - Go and install our reliable trailer, enjoy the happy time with your pets or kids. Package list: 2 x traction adapters