Bike Trailer Coupling Compatibility: Fits most bikes as well as disc brakes and Instep brand trailers. It is not for BREEZER style dropouts. For QR axle and 12mm (outer diameter) solid axle, approximately equal to 0.48 inches). High-quality material: high-quality iron, solid structure, excellent structure, outdoor long-term use of high-quality trailer coupling. Precise design: the diameter of the hole connected to the bike is 1/2 inch, and the outer diameter of the part connected to the axle is 1 inch. The hole in the trailer is 1 inch in diameter. 12mm straight axle needs to be adjusted straight axle. This replacement axle has external threads. Family Fun: Additional trailer coupling accessories, family bike can be equipped to pull a stroller, your child or pet will enjoy riding a bike. Brand new and high quality: High wear resistance and excellent durability. Color: black Material: iron Package Contents: 2 x Tow Hooks Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3 cm.