Bicycle Trailer Coupling Compatibility: Suitable for most bicycles as well as disc brakes and entry-level 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 bicycle 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 must be adjusted straight axle. This replacement axle has external threads. Family Fun: Extra trailer hitch accessory coupling, family bike can be equipped to tow stroller, your child or pet will enjoy the fun of cycling. Brand new and high quality: High wear-resistant and excellent durability. Color: Black Material: Iron Package Contents: 2 x Tow Bodies 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 to look slightly different from the real thing. The measurement allowed error is +/- 1-3 cm.