The regulations relate to the diesel fuel and kerosene excise tax and reflect changes made by the American Jobs Creation Act of 2004 (Act) regarding mechanical dye injection systems. Under the Act, diesel fuel and kerosene that are to be used in a nontaxable use must be indelibly dyed by use of a mechanical dye injection system that satisfies the requirements set forth in the regulations. The purpose of the regulations is to establish standards for tamper-resistant mechanical injector dyeing that are reasonable, cost-effective, and set levels of security commensurate with the applicable facility.