This 6-pack of PRITECH Callus Removers Refills has been designed for breaking down rough and tough hard skin. Specifically Designed for Use on Dry Skin Diamond Crystals: Precious exfoliators- genuine Roller Heads are made with finely ground diamond particles which can give you soft, smooth feet in no time at all. Fit for most electronic pedicure foot file brands. Easy to Replace: The roller head should be replaced when it starts to show signs of wear which depends on the intensity and duration of the treatment sessions. Install Steps: 1.Turn Device Off: Remove the roller by pressing the eject button on the side of the unit and gently pulling the roller away. 2.Insert New Roller Head: Place the new roller into the unit by pressing in the pins on either sides of the roller head and inserting the head into the device. 3.Buff and Smooth: Check that the roller head is securely attached to the device before use.