The Superior 4 takes an already lightweight, fast trail shoe and makes it even lighter. The upper has been completely redesigned in a wrap-around style for added security and support; the midsole features Altra's proprietary Quantic(TM) foam, while the outsole is now made of sticky MaxTrac(TM) rubber. To top it off, the rounded heel and improved lug pattern is made to fly down the trail with ease and speed. Features: - Seamless wrap-around engineered knit upper - Balanced cushioning and zero drop design encourages proper, low-impact form - Footshape toebox allows your toes to relax and spread out naturally for more comfort and stability in uphill climbs and downhill descents. - Altra Ego midsole has a responsive yet soft feel for increased energy return - Trailclaw canted lugs are positioned strategically beneath the metatarsals to provide traction at toe off. - GaiterTrap hook-and-loop trap allows strapless gaiter attachment - 6mm Contour Footbed with removable StoneGuard(TM) - Stack Height: 21 mm