The two exchange membrane electrodes in this demonstrator are 35mmx35mm. Experimental steps: Add deionized water to the PEM water electrolyzer to the water level line. The amount of water should not be too much to prevent water from flowing into the battery. After adding water, use the air pipe to connect the hydrogen gas outlet on the water electrolyzer to the hydrogen gas inlet on the battery. Then connect a 6V-12V DC power supply to the positive and negative terminals of the water electrolyzer part. After 23 minutes, connect the connection wires of the electrical part to the battery. The small motor starts to work, and the current and voltage values are displayed on the ammeter and voltmeter. Name:Hydrogen Fuel Cell The demonstrator is mainly composed of the following four parts: 1. Electrical part: with fan motor, ammeter, voltmeter. 2. Hydrogen fuel cell. 3. PEM ( exchange membrane) water electrolyzer. 4. Organic base Notes: 1. Do external voltage to the voltage output terminal, otherwise the fuel cell be 2. Store PEM fuel cells in sealed containers 3. When using hoses for connection, that all connecting parts and hoses are airtight 4. Do not disassemble the PEM fuel cell, otherwise it may cause damage. 5. Special note: The positive and negative polarity on the PEM water electrolyzer cannot be connected incorrectly. Once connected incorrectly, it cause damage to the battery and electrolyzer or even unusable. Colour:As Shown Material:Plastic Package Contents: 2 x Hydrogen Fuel Demonstrator 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.