Altra - The Difference of Three. Altra's FootShape toe box allows the toes to relax and spread out naturally and the big toe to remain in a straight position for maximum stability and power. Altra's Fit4Her technology caters to the specific form of the female foot, which has a narrower heel and midfoot, a higher instep, a longer arch and unique metatarsal spacing. Every Altra shoe is built on a Balanced Cushioning platform that positions the heel and forefoot an equal distance from the ground. This natural foundation aids in optimal alignment, cultivates better form, and encourages a low-impact landing.