The products which are suitable for electronic enthusiasts to study and repair circuits. The installation of the circuit requires the buyer to have experience in the circuit. This circuit is an innovative design for dynamic electronics. After being powered on, the thumb like pattern composed of 81 LEDs presents various flashing effects. Press button S2 to adjust the water flow speed. Note: This is DIY kit, not a finished product. You will need to solder it yourself. Installation precautions: All light-emitting diodes and microcontrollers have polarity components. Be careful not to install them upside down. If you need other colors or colorful effects, just replace the LED. Introduction to Circuit Principles 81 LEDs are connected to a dedicated microcontroller DX158 through a combination of rows and columns, and are scanned and driven to light up in the desired way through the microcontroller program. The microcontroller program in this kit has been burned and welded to produce the desired effect. DC1 is small DC socket, It can be powered by 4-5V DC, and can be powered by any 5V charging head. ( 5V charging head Not included). S1 power switch, C1 is a backup filter capacitor, which generally does not need to be installed and is not provided in the kit, which does not affect the effectiveness of use. Color: Black Material: PCB Package Contents: 1* DIY kit 1* Power cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.