I bought this tuner with my CR 209 Violin at Sam Ash. While I'm tuning my violin, the screen light flickers on and off. This seems to be caused by the battery cover getting loose and the battery trying to pop out. When I press down the battery cover, the light goes back on. Without the light on you can't see anything. It's not like a backlight on an alarm clock. When the light is on the tuner works properly. But it can suddenly go off. I wouldn't recommend this item, it's poor quality.