Lets Go Pet Walker, Hands Free Bicycle Dog Leash for Medium / Large Dog. 4 Colors, Gold, Purple, Blue, Red Easy install and quick release, no tool needed Safety- Dual spring/ single spring provide elasticity and avoid an unexpected pulling force while your dog meets your neighbor's cat. A biker will not be controlled by the dog and Unhindered - Won't interrupt a biker's thigh Fit for Small/ Medium / Large Size Dog Fit all kind of bike - Fit all size seat post 25.4-31.8mm Light weight - Only 350g*. All aluminum made. Aluminum 6061, various color: Blue and Red