This Self Heating Sleep Mask Emits A Comforting Warmth; Sit Back As The Warm Steam Gives Your Eyes The Relief They Deserve; Use This Warm Compress To Relax After Long Day. The eye mask itself is made from non woven cotton, each heat cell contains iron powder, vermiculite, activated carbon, salt and water, all naturally occurring ingredients. The mask is fragrance free and free from artificial ingredients.
When the pouch is opened, the iron powder inside heat cells reacts with oxygen in the air causing it to heat up gently. The mask reaches a maximum temperature of 100.4 F or 38 C and stays at this temperature for at least 20 minutes.