Adult KJ XR3 jumping boots are designed for sizes 34–48. The most common sizes are S and M. Size S is ideal for shoe size 36–38 (exceptionally up to 39 if you are between 38/39). Size M fits perfectly for size 39–41. Size L is for 41–43, and XL for 44–48. Children’s Powershoe boots are designed for kids with shoe sizes approx. 30–35 (XXS) and 35–38 (XS); both sizes are suitable for weight 15–45 kg (the spring can be easily adjusted). Not sure what to do? Contact us and we will gladly help you choose the right boots for you