This is our flagship barefoot sport sandal for barefoot activities. Base is molded silicon with an adjustable nylon strap and a D-buckle for easy on/off and adjustment. Fully waterproof, hypoallergenic, durable support for going barefoot either on land or water. The Medium size covers a range of shoe sizes due to only needing to span the width of the foot. It is flexible and wraps around slightly to accommodate different shaped feet. Medium is recommended for anyone with a small or medium size foot. Women's size 7-11 approximately. Comes with a nylon mesh drawstring bag to rinse and dry after use and for storing.