For someone looking for what I consider the Cats Meow of test lites, try it.
Details: 20ft lead, 20ft extension lead, hooks to battery with clamps or to lighter socket with supplied adapters, red/green LED to indicate power/ground, 2 tones to indicate power/ground, twin LED "headlites" to illuminate probe. This works out great since you don't have to move the connections when moving from under the hood to under the dash. The unique feature is that the PPII can actually power up a component with a switch n the handle or run a ground to a component with the same switch. The circuit is protected with a resetable circuit breaker( amperage i don't know, but it will power the condenser fans on AC. Price, about $100

 

I've bought two. First one, a Power Probe I with another tool for $69. off of evilbay. Used it so much that the shop kept borrowing it. I upgraded to the Power Probe II (second generation due to the change in ground detection). Prime examples of how usefull it's been, testing a fan relay and one particular car, the shop was split 50/50 on wether it was the fuel pump or the fuel pump relay. I pulled out the power probe, another mechanic pulled out the standard test light and we went to town. It was both, saved time on that way too busy day.