Left and right asymmetrical, non-metallic carbon-fiber toes offer unobtrusive fit and are 15% lighter than steel. Oil- and slip-resistant non-marking rubber outsole. Electrical hazard (EH) or Electric Shock Resistant (ESR) footwear provides a secondary source of protection incase accidentally coming into contact with live electrical circuits. 900 heel (5/8" Height) provides stability and helps "catch or lock" the foot in place. KEEN Bellows Flex. KEEN Luftcell: Air-infused, PU midsole for weightless comfort. Direct attach PU construction creates a strong bond between the upper and outsole without the use of glue or cement. Contoured heel guard protects against bumps and scrapes, plus normal wear and tear. Dual purpose metal lace hooks.