Lightweight. Fast. Grippy. Fast. Responsive. Fast. There are many words to describe the speedy Altra Superior 4.5. The Quantic™ midsole offers a lightweight yet responsive ride for high-speed trail days. The MaxTrac™ outsole and multi-directional lug pattern brings grippy traction to any terrain. The improved upper brings better breathability and durability. And finally, the removable StoneGuard™ offers lightweight rock protection for when the trails get extra rugged.