1. Bicycle hitch adapters are crafted from steel and feature a durable black enamel coating. Utilizing precision welding technology, they are resistant to breaking, rust, or corrosion, ensuring longterm reliability. 2. **Trailer Coupler Dimensions**: **Bicycle Connection**: Hole diameter: 0.43 inch (11 mm); Screw nut diameter: 0.87 inch (22 mm). **Trailer Connection**: Embedded part hole diameter: 0.27 inch (7 mm); Length: 0.98 inch (25 mm); Insert part diameter: 0.5 inch (13 mm). 3. **Unique Design**: Each bicycle trailer hitch includes a connecting pin. Simply attach the hitch to your bike with the screw nut, insert the trailer attachment, and secure it with the pin. Once installed, the coupling remains firmly locked, preventing accidental detachment for enhanced safety for children and pets. 4. **Wide Compatibility**: Ideal for mountain bikes, folding bikes, strollers, shopping carts, pet trailers, cargo transport, and more.