Dr. Andrew Weil Women's Spirit 100% Leather Rubber sole Heel measures approximately 3/4" Full-grain leather uppers Aymmetrical two buckle with adjustable straps for a more custom fit. Recycled slip-resistant rubber outsole Orthaheel technology - Dr. Weil often recommends Orthaheel Sandals for overall foot wellness. The same pronation control technology used in the sandals are found in Dr. Weil Integrative Footwear. 1st Ray Flexor Zone - assists forefoot mobility and gait (walking) efficiency by providing extra cushioning and flexibility at the big toe - assists in 'toe off'.