Mens Large 10-12 Womens 11-13 Has A Semi-rigid Strap That Pulls The Toes Upward And The Foot Into A Slight Dorsiflexion Position This Gently Stretches The Plantar Fascia So It May Heal The Combination Of The Thermal Properties That Help Reduce Inflamation And The Stretching Of The Plantar Fascia While Sleeping May Aid In The Treatment Of Plantar Fasciitis Non-slip Safety Soletm Rubber Grip Bottom Helps Prevent Slipping