Description: Carbon steelBicycle trailer hook accessories are made of carbon steel, durable, not easy to damage and deformed, and can be reused without replacement. Security ProtectionEach 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 InstallIt is very simple to install the bicycle trailer hook joint to the rear wheel of the bicycle. Just make sure it does not rotate when tightening, then pass the wrench through the pin hole and fix it in place when tightening. Wide ApplicationBike trailer hitch coupler is not only suitable for mountain bikes, folding bikes, bicycles, etc. But also very suitable for all kinds of common strollers, pet carts, trailers, etc. Package And SizeThe package contains 1PC bicycle trailer hook connector. Bike trailer hitch coupler size is only fit for QR shafts and solid shafts up to 11.8 mm / 0.45 inches. Installation Procedure: 1.Open the quick-release lever, and remove the nut and spring from the opposite side. Hold the lever and pull the axle skewer with spring out.Completely remover the skewer but leave the wheel in place. 2.Slide the coupler onto the skewer.(The wide end of the spring should face out and touch the lever, the bell of the coupler should face out, and the tab washer hook should face in toward the wheel hub. 3.Insert the end of the skewer through the wheel hub, replace the spring (wide end out!) over the end of the skewer,followed by the nut. 4.Adjust the coupler to a right angle and tighten the nut by hand and clamp the lever. Connect the trailer with the coupler by a Q/R pin. Specification: Material: carbon steel Feature: easy to install Color: black Size(approx.): (L x W x T): 5.7 x 3 x 0.4cm/2.24 x 1.18 x 0.16inch the diameter of a great circle: 1.18cm/0.46inch the diameter of a small circle: 0.7cm/0.28inch Package Included: 1 PC x Bike Trailer Hitch Coupler Note: 1. Due to the light and screen difference, the item's color may be slightly different from the pictures. 2. Please allow 1-2 cm differences due to manual measurement. We usually ship orders in 48 hours when payment is verified. If you have any problems about the order, please justcontact us. We try our best to help!