DimensionWe have 2 bike hitch and 2 connecting pins. Diameter of the hole where the axle is attached: 12 mm. Installation diameter to which the axle nut is screwed: 22mm. Diameter of the hole in the hitch where the trailer is attached: 7 mm. Base plate length: 55mm. Quality MaterialsUniversal bicycle towbar is made of high quality stainless steel and the surface is coated with black enamel. It is rustproof, strong and durable, anti-corrosion, difficult to damage. Easy to UseOur bike trailer is easy to install, no other tools required. First, attach the hitch of your bike trailer to your bike with a nut. Then insert the hitch, the metal hitch is easy to integrate with the trailer holding pin and flex connector. SecurityThe universal bike Towbar suitable for all kinds of ordinary strollers, bicycles, Very suitable for family and towing vehicles. Due to the high mobility of the trailer, you can easily drive on wide roads, you can also react to sudden dangers in time! Note: Please measure the size of your towbar and bike mount before ordering. Scope of applicationThe metal hook has excellent durability and is compatible with most bikes on the market. It is suitable for all types of normal strollers. The trailer connector can easily connect the trailer to the bike. At the same time, the baby can be transported safely and comfortably.",