Tests for defective alternator diodes including GM trio test, and performs complete battery test as well. 125 Amp load checks state of charge on conventional and maintenance-free batteries. Searches for excess starter current and alternator/regulator output voltage. Light weight, hand-held convenience. Digital accuracy performs these tests AUTOMATICALLY: - State of charge - Battery load test - Starter test - Charging system test Lightweight and easy to use Recessed meter to protect from damage Made in USA