[20 pieces] - Coarse black × 8, effective and fast for removing thick calluses, suitable for very hard skin; medium blue × 8, suitable for normal and hard skin; fine white × 4, suitable for daily foot care.;[Use different grits] - Choose the right roller depending on the condition of your foot skin. You can use a high-grit roller to quickly remove hard, rough skin, and then use a low-grit roller for fine-tuning.;[Wide compatibility and packaging] - This product is compatible with Scholl Velvet Smooth, Scholl Velvet Smooth Wet & Dry and Scholl Velvet Soft. Note: Not compatible with Scholl Express Pedi.;[Good quality, easy to clean] - The cheapest price, most parts. Our replacement rollers have twice the hardness with micro-diamond crystal abrasive grains, which are wear-resistant and remove dead skin more effectively. Washable materials ensure quick and easy cleaning.;[Recommended method of use] - It is recommended to clean the sanding head after each use, and to replace it with new accessories every 10 to 12 times, or after 50 minutes of use. Do not use more than 2 times per week and do not use the same area for more than 3 seconds to avoid skin damage.