Pet Harness, Medium in Reactive Your pet deserves only the best — which is why this fleece lined harness is the perfect addition to your morning walk routine. Available in three sizes for a comfortable fit. Fleeced lined Available in three sizes Weight capacities for each size are as follows: Size small (10 – 25 lbs.), size medium (25 – 50 lbs.) and size large (50 – 90 lbs.).