Exped SIM 3.8

The Exped SIM 3.8 is a self-inflating sleeping mat with a 3.8 cm open-cell PU foam core. Open the valve and the foam draws in air on its own, filling most of the mat without extra breaths — a design that trades some weight for puncture resistance and simplicity compared to pure air pads. Its ASTM R-value of 4.6 puts it in the 3-4 season range, suitable for cooler spring and autumn nights as well as summer use. The top fabric is 75D recycled polyester with a TPU laminate and honeycomb embossing that helps keep a sleeping bag from sliding around; it carries Oeko-Tex 100 certification and the pad is PFC-free. Two flat, low-profile valves, Regular size (183 × 50 cm), 860 g weight, and a 26 × 18 cm packed size round out the spec sheet. A stuff sack, repair kit, and 5-year warranty are included. At 860 g this is not a pad for gram-counting thru-hikers, but for weekend and multi-day trips where comfort and reliability outweigh shaving grams, it delivers a solid warmth-to-weight balance.