Unlike other boottype night splints the Strassburg Sock® provides clinically proven relief from Plantar Fasciitis by providing gentle tissue specific stretch directly to the plantar fascia by engaging the Windlass Mechanism. Efficacy demonstrated in the largest independent, peer-reviewed night splint study ever conducted. Plantar fasciitis average recovery time 18.5 days and 97.8% recovery rate within 8 weeks. Also effective for achilles tendonitits and tight calves. Contains no latex. Fits right or left. Measure calf circumference at widest point to determine size.