The angled topline offers a more comfortable fit around the calf while the extended rubber upper offers additional protection. this boot will be a classic for years to come. 5mm cr flex-foam. Breathable airmesh lining. Extended rubber coverage. Angled topline. Achilles reinforcement. Aggressive waffle high traction outsole. Cr flex-foam adjusts to the unique contours of your foot to create a comfortable and stable foundation while resisting blisters and chafing