The Wizard Galvanometer Demolition Safety Light (DSL) is designed specifically for checking the continuity of firing circuits and electrically initiated pyrotechnic devices.
It's easy to use - just touch the leg wires to the copper disks and the red light will come on, indicating a complete circuit.
2 year battery life expectancy with proper use. (Accidental connection of poles while stored will drain the battery in under a week.)
What's more, it checks circuits using a meager 5 mA—one tenth the safe limit established by the Department of Labor.
2 x 1 x 3/4 (LWH in inches)