I created caps to allow for comfortable on-the-knee use with adjustable dumbbells. Using these will prevent you from experiencing pain from the shaft. This is a listing for a set of 2 caps (dumbbells are not included). I have sold over 180 sets so far. If the caps are damaged within 2 weeks of use, provided the usage instructions are followed, I will replace them free of charge. The size is slightly smaller than a 1.25kg plate to prevent damage. I use IROTEC screw-type dumbbells, but I believe they can be used with 28mm screw-type dumbbells. I was able to use 3-4 plates, including the collars. * The screw part needs to be exposed about 1.5cm for attachment. Each cap weighs approximately 70g. The material is durable ABS. I have been using them for about six months after creation, and there has been no damage. (25kg weight, used every other day) These are handmade items, so please understand that there may be small burrs, dents, and scratches. ☆ Usage Instructions ・Although the photo shows the dumbbells standing up, please refrain from doing so as it may cause injury or damage. ・Do not overtighten the caps, as this may cause damage. ・Do not drop the dumbbells, as this may lead to damage. ・Do not use the caps themselves as collars, as this is dangerous. ・Avoid direct sunlight, as it will accelerate the deterioration of the material. ※ Please note that I cannot offer discounts on this product. ※ Please be aware that I only sell these on Mercari.