Any specialty tool will help make an automotive repair or maintenance task easier, but Powerbuilt products take the concept of ‘help' a big step further. Every package comes with professionally written usage instructions that take you step by step through proper tool usage. This computer safe circuit tester is fit for a wide variety of systems, from 3 volts on up to 28. All Powerbuilt products meet or exceed applicable ASME, ANSI and US government quality standards and are backed by a lifetime warranty on all tools.