Handy device for testing LED's. Simply plug your LED into the correct holes (all of which are marked) and push the button to see its brightness, color, etc.
The top row is for 2 pin LED's with currents ranging from 2mA - 30mA,
The bottom row is for 4 pin LED's (piranha LED's) with currents ranging from 20mA - 150mA
Powered by a 9V battery (not included)