If comfort, durability and ease of use are important to you, our self-inflating Exosphere 3.5 sleeping mat is ideal. The X-Core foam filling provides support and insulation for a restful night's sleep so you're ready for the next day's adventures. This foam uses X-Core technology, a three-dimensional, weight-reducing structure. This saves weight and reduces pack size, but also traps air to increase warmth, contributing to the mat's R-value of 3.4, and the rectangular shape lets you sleep in any position. In threatening weather, the mat inflates in an instant thanks to its low-profile, two-way design, and it rolls up just as quickly when you want to put it back in your pack. Made from polyester with a fluorocarbon-free DWR coating, the Exosphere 3.5's outer fabric is durable yet feels very soft against the skin. The versatile and reliable sleeping mat is ideal for various purposes and the perfect place to rest and plan the next day.