[20 pieces] - Thick black 8, effective and fast in removing thick cuticles, suitable for hard skin; Medium blue 8, suitable for neutral and hard skin; Fine white 4, suitable for daily foot care.[Use different roughness] - Choose the appropriate roller according to the condition of the foot skin. You can use a rolling pin. High roughness can quickly remove hard and rough skin, and then use a low roughness roller for fine sanding.HIGH-QUALITY ABRASIVES: These replacement grinding heads are made with premium abrasives to effectively remove stubborn calluses and dead skin. They provide a smooth and efficient foot grinding experience, leaving your feet feeling soft and refreshed.[High Quality and Easy to Clean] - The most affordable price with the most parts. Our replacement rollers are twice as hard as regular rollers. Micro diamond crystal abrasive grains are wear-resistant and more effective in removing dead skin. Washable material for quick and easy cleaning.Recommended Usage - It is recommended to clean the sand head after each use and replace new accessories every 10 to 50 minutes. 12 times, do not use more than 2 times a week and the same piece of use time is no more than 3 seconds. Avoid damage to the skin.