10 x Eye Relax mask and 1 booklet (not for retail sale) - self-warming eye mask - heat for 20-25 minutes Oxygen molecules in the air combine with a thin layer of iron filings and activated carbon. This creates a completely safe heating process — anytime and anywhere. Immerse yourself in a world of warmth and relaxation. The pleasant warmth helps you relax or fall asleep. Tired and strained eyes will love this wonderful mask. It's that simple Open the pouch and unfold the mask. There are two fabric ear loops on the inside of the mask that you need to separate from the mask. Carefully place the mask over your closed eyes and put the loops around your ears. The mask heats up immediately when removed from the bag as the oxygen from the air reacts with the iron powder.