L-1 Digital Tuner (CPO)

From the manufacturer:

• Two sources selectable with switch. Multiples to use a signal further.
• A4 button Select A4 frequency in the range 430-450Hz.
• ON button. If to hold the button 1 sec, turn the screen off/on. Momentary press select tunning item: Chromatic, Guitar, Bass, Violin, Ukulele. Default position is Chromatic. No need to change.
• If no wave at the input or a wave is out of the range, screen will turn off in two minutes. If it happened just press ON button 1 sec to turn the screen on.
• Power consumption: V+ 7mA, V- 0mA.