The Exped SIM Comfort Sleeping Pad is the California king of camping comfort. Four inches of dreamy refuge from the cold, hard ground will help anybody get their much needed beauty sleep. The laminated polyester surface fabric is durable, airtight, humidity resistant, and has a non-slip finish. SIM stands for Self Inflating Mat, which means you just open the valve and let the laws of physics do all the work. A stuff sack and repair kit are included.