Testing tinted window light transmission has never been so easy since the development of the Laser Labs Model 100 Tint Meter. To operate this device, roll a car window down half way, place the Tint Meter directly over the window, and slide it down inserting the glass into the meter. Within seconds the light transmittance reading is displayed. Slide the meter off the window, and the device automatically turns the power off, protecting you against drained batteries. The Tint Meter works just as well in bright sunlight as it does on moonless nights. A nine volt (9V) battery is all that is required. Each Model 100 is supplied with two (2) N.I.S.T. traceable reference samples to verify the meter's accuracy.