Men's ALTRAA(R) HIIT XT :: Fully engage intense training in your new, Men's Altra HIIT XT training shoe. Blast off from the stable PowerSole(TM) outsole for balanced energy output. Go from a 24mm to an 18mm stack height with a removable insole giving you a lower natural stance that's equally comfortable. Cut on a dime, jump and climb with the Wrap-Around Gum Rubber Outsole giving you grab and response. Dish out your hardest workouts cuz the HIIT XT mesh upper is built for high-intensity, gym and CrossFit(TM).