This crystal hair eraser uses nanocrystal technology, all you need to do is simply rub it to your skin in a CIRCULAR MOTION for a hair-free body! No need to use excessive force, just patiently and gently do circular motion, this magic crystal hair remover will work well and won’t hurt the skin. It is safe to use on knuckles, arms, legs, chest, and back. However, we suggest not to overuse or rub too hard. If you have sensitive skin, try it on your arms/legs first before you use it on other delicate parts. Warm tips: treated by warm water before using