With these pillows' main materials being mineral oil and dry polymer,the resultant material is however relatively expensive when comparedto produce compared to foam. Gel has a very high tensile strength and is extremely durable. It is guaranteed to not compress or permanently deform for 5 years. A naturalvibration and shock dampener, this material helps to significantlyeliminate travel fatigue. Features:1) 1cm embedded layer of soothing gel over a contour shaped memory foam pillow2) The air chamber constructed surface provides great air ventilation between the user's head and pillow for super cool sleeping3) Gel material side: consisting of numerous air chambers, this material elevates the user's head and provides a great airy feeling in summer4) Providing pleasant dry and airy sleeping conditions, these pillows are absolutely great for use in summer5) Gel layer gently cradles the user's head, neck and shoulders for a restful, floating sensation6) High-density, contoured memory foam supports head, neck and shoulders to allow muscles to relax (rather than tense up as with regular pillows), and helps keep the neck and spine properly aligned for a restful sleep producing area:China