This is not a toy! It is a serious spy mic, with super stable PLL frequency synthesizer, tunable for a frequency between 76 and 108MHz, with 100mW output power. It works out of the box, but can be programmed using a Windows program (link supplied with delivery).
The necessary operating voltage is 3-5V DC, the average operating current is 35mA. Please add an appropriate piece of wire as antenna (1/4 wave length = 75cm, for example).
You will also need a USB-TTL adapter for programming (for example CH340G or FT232), if you want to change parameters.
Dimension of the module: 10 x 25 x 4mm, weight 0.9g