My son used this for just under a year when he was in 5th grade. We had been renting until we bought this when he was in 2nd grade, and the size was about the same as the rental, so it was a good size for grades 2-5. When my son (small for his age) was in 2nd grade, a friend two years younger than him was renting the same size, so I think it could be used from kindergarten. Currently, he's in 5th grade, 140cm tall and slender. This one still fits him perfectly in terms of size, but I'm selling it because I bought a set one size larger due to an acquaintance who owns a bogu shop. The new one is wider, so in terms of ease of movement, the one I'm selling seems easier to move in. He was busy with entrance exams and lessons, and didn't go to the dojo very often, and there weren't many kids who hit the torso, so there are few scratches and I think it's in good condition. I bought this after it was recommended by a bogu shop that kids in this area go to. It's a Yamato Do. From the website: The Yamato Do SS size is a lightweight and durable kendo do mainly for young children to lower elementary school students. It uses Toray's nylon resin "Amiran," which is impact-resistant and easy to maintain, making it popular for growing children. The size was measured according to the attached image. This seems to be the SS size. A 30cm Do height B 27.5cm C 13.5cm Chest height D 19cm Chest width E 18cm F Do circumference (half circumference) 54cm