With this  kit you can build a useful megaphone or PA system to amplify your voice. This kit is small and self-contained and includes a high-gain electret microphone, an IC audio amplifier, a volume control and a speaker. You will really be amazed with the clarity of sound and power of this little amplifier system. Ideal for use as a megaphone, PA system, one-way intercom, or many other applications where sound needs to be amplified. Approximate size of board: 1 3/4" x 1 1/4". Operates from a standard 9V battery (not included). Complete with all parts, PC board, and instructions. Skill level beginner.