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 Five Fingers. The KSO is and 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 xs trek performance rubber soles are razor-siped for sure grip.