First and only of its kind!! Simply screw in and turn on power. Internal lamps indicate if the starter (ignitor) or the ballast need replacement. Suitable for H.I.D. ballast circuit with a starter. Checks starting pulse voltage and open circuit voltage. Can be used on High Pressure Sodium, Metal Halide and Mercury Vapor light fixtures. Two models available, medium or mogul base. Order one or save $20.00 buying both today.