The Z Seat from Therm-A-Rest has many recesses to trap the warm air & insulate you from the cold ground, helping to keep your bum warm when you perch yourself for a rest or for a spot of lunch. The closed cell foam construction, instead of a blow up construction, means it is completely puncture proof. The Z Seat is highly versatile, light weight, & comfortable. Closed cell foam construction No chance of punctures Lightweight