This product is .83HZ low frequency generator, features high accuracy and stability. High stable frequency acquisition : high stability pulse chip, precision correction capacitance, precision multi-loop adjustable resistor. High quality polymer batteries, with overcharged, overvoltage, overcurrent protection. There is no voltage ripple in the voltage supply. wave can be applied to HIFI or sleep. material: plastic colour:Random Color Note: Random color, 't accept the specified color. Package Contents: 1 x wave generator 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.