The Men's KSO is Vibram's most popular footwear and can be used for a number of activities including running and gym work. The KSO's keep it simple with a durable rubber outsole of a mere 3.5mm in thickness, designed to give a high level of ground feel and excellent traction on wet or dry surfaces. Although protective, the outsole is very flexible, allowing for your foot to flex naturally without restriction. The individual toe pockets and the flexibility of the sole help to engage muscles in your feet that are rarely used, this will help to strengthen your feet and lower legs. The upper is a stretchy polyamide fabric that fits close to the foot and features a Velcro fastener to secure the foot. For added comfort inside the shoes is a soft 2mm thick EVA foot bed with antimicrobial properties to will keep them fresher for longer.