This is a refill cartridge for the Automatic Eye Pencil Duo. The snap-in, snap-out cartridges let you create your own custom eye tool. For example, if you have an Automatic Eye Pencil Duo in one shade, try a refill in a second shade. Just snap out the smudger cartridge and snap in the second shade for an ultra-convenient and very versatile tool. Suitable for contact lens wearers.