Quantity : One piece (with buckle) Bike Trailer Accessories: Bike mounting holes are 11mm and trailer mounting holes are 7mm. You must confirm that your trailer can be installed before purchasing. Happy Ride: With a trailer hitch, the bike can be used to tow a child's trailer, and you and your family can take turns take your adorable pet on vacation Enjoy wonderful outdoor excursions and great vacations. Simple Installation: Installation requires removing the nuts and bolts from the rear wheel, making it easy to install without additional tools, and finally attaching the Axle towing hitch Wear-resistant material: Made of metal material, it is resistant to deformation, not easy to damage and wear-resistant. You can even use it to replace worn or damaged parts. Safe and stable: Each bicycle trailer connector is equipped with a connecting pin, which is not easy to open and not easy to fall off , which can guarantee the safety of children and pets.