Voltage Tester. Clip is negative and point side is positive. You must have it connected correctly otherwise voltage will not show.
Cable length approx 4 ft total length over 4.67 ft 
Extra large clip for battery terminals etc.
-reverse polarity protection.
- For DC 2.6V -30V.
Max. Input Voltage: DC 30V(Higher than this voltage is has a risk of overburning).
The precision automatic adjustment, when less than 10V accurate to 0.01V, more than 10V accurate to 0.1V.