The size is listed as size 1, and I think it was for dogs up to about 2.5 kg! However, my dog is a little over 2.5 kg, and I used it once or twice, but I thought it was a bit small, so I can't use it anymore and will give it away. (´；Д；`) It's in perfect condition, so please consider it! (о´∀`о)✨ Please ask about price reductions in the comments! ☆Please use it with a plain leash you already have, etc.☆