Springer Dog Exerciser, Biking with your Dog Springer Leash, the bike attachment that allows you to safely bike with your dog. This unique dog exerciser can bring health benefits for you and your dog as you pedal and jog side-by-side. The device has a heavy-duty steel spring, situated low on the arm to absorb up to 90% of the force of a dogs unexpected tugs It does not include a harness. Please use a harness that is suitable for your particular breed. Do not use a regular collar which may injure your dog. Can be used on either side of your bike