The patented Merrell Air Cushion Midsole absorbs shock and adds stability. It is found exclusively in Merrell footwear. The Air Cushion compresses on heel strike to absorb shock up to four times the body's weight for unmatched support and comfort. In addition, the Air Cushion creates a pronounced heel cup, which keeps the heel centred in the boot and helps stabilize the foot. In short, it offers the comfort and cushioning of a running shoe, with the stability and control needed for backcountry travel. No bladders or capsules to pop or explode!