These AC power supplies are the sourced from IT equipment suppliers originally for expensive network equipment; these are removed from retired equipment or spare unit storage. As a result, they produce highly filtered power with precise 12v regulation for clean output power from any 120v AC outlet. They are updated to make them easy to use with our RC LiPo chargers. Tested at high power prior to sale. The units have short protection. The units have over current protection. The units have thermal protection. The internal cooling fan is automatically regulated. It ramps up and down based on heat. This supply comes with USB output to power devices such as diff checker, USB lights, etc. Note: These units are not intended to be hooked together in series to create 24 volts. These kits come with AC power cord and correct size bullet connectors for soldering to your charger cable.