▶Don't worry,the leash is very thick，so you don't worry he'll be able to chew through it. ▶Leash is 51' length x 0.59' diameter for small, 51' length x 0.78' diameter for large. No pull collar fits neck size 12.9' to 16.4'(33cm to 42cm) for small, 16.9' to 20.8'(43cm to 53cm) for large，Breeder highly recommended. ▶360°Swivel rotating action of the leash-collar connection prevents twists for maximum convenience ▶Have cushioning protection, avoid the pet's neck injury due to pull violently ▶100% MONEYBACK GUARANTEE - No matter you and your dog not like it, no problem, get your money back! or get this new cool leash for your dog today, it's also a great gift idea!