This product is size SM! I was unsure of the size, so I bought two sizes. It's a beautiful item, only tried on once♪ *Washer after trying on Since it's sleeveless, it can be worn by dogs with short legs or cats♪ It can be used for walks or as pajamas(^^) My pet is around 3.5 kg and wears size M, but depending on the individual, some will fit perfectly, while others will be a little loose. (I wanted to dress them according to their height, so we use a slightly larger size.) Please use the size feeling as a reference. Please measure your pet and consider accordingly m(__)m The neck has some stretch♪ The fabric is fluffy and very comfortable(^^) If you have any questions, please feel free to contact us☆