The device is a two-tone electronic siren implemented using a single NE556 integrated circuit, which contains two 555 timers. The timers operate as multivibrators. The first timer generates a clock signal with a repetition period of approximately 0.5 seconds and controls the second timer, which generates the audio signal.
The output signal from the timer is amplified by a transistor-based low-frequency amplifier.
The siren operates from a DC supply voltage in the range of 9 to 18 V.

Technical Specifications:
Integrated circuit: NE556 (dual 555 timers).
Generator type: clock and audio multivibrator.
Switching period: approx. 0.5 s.
Amplifier: transistor-based.
Supply voltage: 9-18 V DC.
PCB dimensions: 47 x 33 mm.

This product is a fully assembled module.
It is also available as a DIY assembly kit - Product code 1020 (separate product).