The Surge is a mid calf boot with a contrasting leathers. This style has a side zipper for accessibility. The Surge features padded technical lining which provides comfort and absorbs moisture. The Surge has a 4.75" shaft. Naot's removable, anatomic cork & latex footbed is wrapped in pampering suede and molds to the shape of the foot with wear. The Shell Collection features a 1.5" polyurethane sole which is extremely lightweight, durable & slip resistant.