Technical information
1. DC Power Supply 9 V.
2. Speaker Piano Solo to drive frequency the sound.
3. Can Selectable frequencies about 2.75 KHz to 14 KHz The adjustment VR1.
4. Have LED1 show When the cycle work.
5. Reverse Polarity Protection.
6. Dimension 2.99 cm X 5.68 cm (1.18" X 2.24").