1、Rugged material: Bicycle trailer hooks are made of high-quality steel, which is sturdy and durable, and is coated with powder paint, it can be perfectly integrated into your bicycle even if the trailer is not connected. 2、Compatibility: Suitable for QR shafts and solid shafts up to 100mm (OD = 0.48 inches), not suitable for Breezer-type releases, and can be used with disc brakes and full suspension. 3、Easy to install: Just make sure it won't rotate when tightening, then pass the wrench through the pin hole and fix it in place when tightening, easy to install, easy to install in a few minutes (not including wrench). 4、Widely used: If you want to ride a bicycle and want your children to be with you, just buy our bicycle trailer, you can have a good family time with the children. 5、What you will get: Equipped with a 1 piece bicycle hook connector and quick release lever for your convenience; suitable for most bicycles, such as mountain bikes, folding bikes, road bikes, etc. 1 x Towing Hook Sturdy material: Made of quality steel, sturdy and durable, well made and strong, coated with powder paint which made it blends into your bike perfectly even when no trailer is connected. Have fun with family: Enjoy the joy and excitement of transporting your kids or pets around with your bikes, just to make sure it doesn't spin while tightening and throw a wrench through the pin hole and hold in position while tightening. Suitable for: This bike hitch coupler can suit for many kinds of bike such as mountain bike, folding bike, road bike, etc. Specification: Colour: Black Material: Steel Size: about 7.5x 7.5x3cm (the diameter of the inner hole of the connecting bicycle part: about 12mm)