Connect Your Kids, Pets, or Cargo This bike trailer hitch mount coupler is designed to attach your kids trailer to your bike, which you can mount on the rear axle of your bike. Premium materials made from durable materials made, resistant to deformation, Not easy to damage, wear-resistant. Durable, reliable parts are available to replace worn or damaged parts. Bike and Trailer Mounting Dimensions The bike mounting hole is 11mm, you can use it on most bikes, easy to install. Trailer Mount The hole is 7mm, you need to confirm that your trailer can be installed before purchasing. Easy to use and perfect for most bikes that use a rear axle nut to attach to the rear axle of the bike. Made of heavy duty steel, welded hook arms approx. With a 45-degree angle, it provides an ideal attachment location for many types of bike trailers. Bicycle rear axle fixing hole diameter: 11mm Link trailer fixing hole diameter: 7mm Axle nut screwed into recessed area diameter: 21mm Bottom plate length: 55mmQuantity: 1-Pack "Bicycle Trailer Trailer Head, Other Products Not IncludedColor as shownSize: 8*5.5*2.5cm (for reference only)Note that due to the color and size difference between the light effect photo and the real object, please allow 1-2 cm error"