Features: Adopting an all metal casing ensures the stability and durability of the pumps, allowing for long term use in various environments. Equipped with an 8mm two phase four wire stepper motor, phase resistance of 22 ohms, voltages of 5V, current of 150mA, achieving high precisely quantitative output. Supporting positive and negatives changes in water flows direction, flexibly meeting different operational needs, and facilitating diversified applications. Using 2.5mm silicone tubing, it has good corrosions resistance and elasticity, suitable for transporting various liquids. The driving voltages ranges is between 3-5V and supports single 3.7V battery power supply. Low voltages may affect the motor speed and flows output. Specifications: Shell Component: Metal Size: As Shown in the Picture Package Includes: 1pc 8mm gearboxes Liquid pumps note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.