When you're scrambling up a rocky bluff or bounding along a riverbank, the last thing you want is gravel and grit seeping into your Fivefingers. The KSO is an all-new design with thin, abrasion-resistant stretch polyamide and breathable stretch mesh that wraps your entire forefoot to "Keep Stuff Out." A single hook-and-loop closure helps secure the fit. Non-marking Vibram TC1 performance rubber soles are razor-siped for a sure grip.