The "Lightning" Level combines Swanson's professional series box beam level design with the power of LED lighted technology. With the use of super bright LEDs, this professional box beam level directly lights all three vials, providing a solution to a common problem: accurately finding level in low-light spaces. The BLL series offers a unique 3-vial Lighted System that is constructed using a single electronic mechanism (on / off button). The on / off mechanism is durably installed into one of the "SuperShock" end cap and is powered by two AAA batteries. In addition to the 3-vial Lighted System, the "Lightning" levels also contain a patent-pending auto-shutoff feature that automatically turns the LED Lighted System off after 10-minutes of continuous run time, to improve battery life.