Arc Flash kits are designed to meet the PPE Category requirements of your working environment. They provide you with the components needed to be in compliance with the new NFPA 70E 2012 standard.
9150-52730
The NFPA has identified the various FR hazardous risk category levels, which range from PPE 1 (which is low risk and requires AR clothing with a minimum arc rating of 4), up to PPE 4 (which is high risk and requires AR clothing with a minimum arc rating of 40). Each level, 1-4, is rated at a certain amount of flame resistance measured in cal/cm2.