This is a TOPPER GEAR power sleeve. It can be used for both elbows and knees, but this is a size S, so it's for elbows. According to the size chart, size S is for upper arms of 28-33cm. I wanted a tight fit, and my arm circumference is 37cm. I was able to wear this, but it was too tight to use, so I'm going to buy a size M. Those who use size S from SBD or P.L. college might be able to wear this. I used it twice at the gym for a very short time, so it's used, and I'm selling it at a low price. Retail price: 4380 yen