Cat eye magnets are used with Cat Eye gel polish over uncured gel polish to create the Cat Eye effect.
Single:
One square magnet which creates a straight line across the nail.
Square magnet pulls the metal particles towards the magnet.
Double:
One square magnet and a round magnet. Square Magnet creates a straight line across the nail. Round magnet creates a curved effect on the nail.
Square magnet pulls the metal particles towards the magnet and the round one pushes the particles away from the magnet.
Choice of single or double ended.