Elvex chainsaw chaps meet the requirements of ASTM Standard for Leg Protection for Chain Saw Users (F-1897-98). This standard requires that the chaps can stop a chain saw running at 2,500 feet/minute under controlled laboratory conditions. (There are no longer two classes of chaps as previously required by the American Pulpwood Association Standard, APA 92-A-12.) The performance requirements remain unchanged at 2500 feet per minute chain speed, tested at both 45 degrees and 90 degrees to the longitudinal axis of the test sample. Compliance tests are performed by Underwriters Laboratories (UL) in accordance with ASTM F-1414, Measurement of Cut Resistance to Chain Saw Lower Body Protective Clothing. Elvex 91 series chaps add wrap around protection around the calves.