Material: The bike trailer hitch coupler attachment made of steel with black enamel coating, made from heavy duty iron material, strong and durable, corrosion resistant, hard to damage.
Universal design: our bike coupler attachment is suitable for QR axles and solid axles up to 12.2 mm/ 0.5 inch, proper for most bicycles and children trailers; Note: does not compatible with Breezer style dropouts
Each bike trailer coupler has equipped with a connect pin, the pins can hardly get opened, also once you install them up, they will not easily fall off, can ensure your babies safety.
Easy to install--- Just to make sure it doesn't spin while tightening, and throw an Allen wrench through the pin hole and hold in position while tightening.
Package include-- comes with 2 packs bike trailer coupler set+2pcs Connect Pin