1.【High quality materials】The bicycle trailer hitch attachment made of steel with black enamel coating, made of durable iron, strong and durable, corrosion resistant, not easy to damage.^ 2.【Suitable size】The diameter of the， bicycle rear axle mounting hole: 11mm， Diameter of the linkage trailer mounting hole: 7mm， The diameter of the recessed part where the shaft nut is screwed: 21mm， Base plate length: 55mm^ 3.【Ensure safety】Each bicycle trailer is equipped with a connecting pin. The pens can hardly be opened. Even after you install them, they are not easy to fall off and can keep your baby safe.^ 4.【Easy to install】First, attach your bicycle trailer tow bar to your bicycle with a screw nut. Then insert the trailer accessory; Finally put the pen; Connection is ready, bring you much convenience.^ 5.【Wide Application】You can use it to pull strollers and pet strollers, and bring children and pets when cycling in the park, which is very convenient and safe.