The MBB Dog Runner gives you a safer way to ride your bike with your favorite pup Features a sturdy seat post mounted bar that extends out from the bike and provides a leash directly above your dog`s collar or harness Leash is spring loaded, and adjustable in both length and firmness to match canines of all sizes and temperaments Quick release mechanism makes removing the extension bar quick and easy when not in use Snap in plastic spacers make adjusting the leash length easy Compatible with 25-35mm seat posts - not recommended for carbon seat posts