Refill for 4 Pack: 4 Regular Coarse for daily maintenance. Perfect Electronic Pedicure Foot File and Pedi Perfect Wet & Dry Rechargeable Foot File and many other brands. ^Grade Materials Replacement Heads: more hard micro-diamond crystals abrasive particles, make it removing dead skin more efficiently, and ultra durable than ever. Washable material design for repeated use. ^Specially Curved Designed refills: Used for Dry Skin to reveal touchably soft,smooth feet. Refillable roller head spins 360 degrees for quick results on thick, calloused skin. The rollers can fit your skin surface perfectly. ^Waterproof material: Waterproof structure ensures simply quick & easy washing and clean in sink, which makes the rollers look like new again.