Rockport Women's Roberts Road Boot 100% Calfskin Rubber sole Heel measures approximately 2 1/4" Adidas adiPRENE and adiPRENE+ footbed pads combine to create lightweight heel cushioning for maximum shock absorption and forefoot cushioning for resiliency adiPRENE is placed in the heel of Rockports footbeds. Its a mixture of EVA and rubber like material for maximum shock absorption that helps cushion upon impact adiPRENE+ lies beneath the forefoot in the footbed. Its a mixture of EVA and a special expanded plastic for rebound that helps you push off