This app helps you to pick the right energy saving light bulb on the supermarked shelf. From the slider you control the brightness and soon youll become used to dealing with lumen for brightness over W for effect. We are all used to having the old style standard light bulb around, in say 60 W, and by using the preset 25/40/60 W buttons in the bottom to get instant conversion to its energy saving counterparts. Supported are low and high voltage areas 120/240 V that is most common. Lumen area covered are 100 to 3.000 lm - that is from from faint to extremely bright.