ALTRA. ALOA4QTQ416. PROVISION 4. ICE FLOE BLUE. The Provision 4 exemplifies the evolution of technical support in running shoes. It is a completely updated and overhauled version of the previous models and is at the forefron of natural biomechanical advances. In addition to a medial GuideRail we ve developed a new arch feature unique to Altra which uses proprioception to help slow pronation and neutralize your step cycle. This feature is a new revolutionary way of offering support only when you need it without interrupting your natural stride. Every type or runner will love this fresh approach to guided natural foot movement.