RED TEK DyeCharge, an a/c leak detection dye from Thermofluid Technologies, is a formulated dye designed to find leaks in rubber parts, o-rings, and metal components of air conditioning and refrigeration systems. RED TEK Pure Zero Patent Pending Technology is a natural, high-efficiency ultra-refined HC gas specifically formulated for use in refrigeration and air conditioning systems. Pure Zero is a Refrigerant Grade Gas made from UL Certified HC gases. Its ultra-refined technology greatly increases efficiency, performance, and reliability. RED TEK PureZero is designed to extend compressor life compared to other lesser refined HC gases that contain impurities not designed for use in air conditioning and refrigeration systems. Some of the largest manufacturers of refrigeration systems have made the switch to RED TEK PUREZERO! IMPORTANT INFORMATION: This product cannot be returned to Amazon.com because it uses flammable liquids and gases, is classified as a hazardous material, or meets other criteria. This is a non refundable, non returnable product.