When you need a real irritating siren, you need the Super Siren Kit. It features one special IC that contains 3 separate transistors and a high gain power amp. Great for getting everyone’s attention in the classroom! The siren sound is the pulsating automatic electronic type and features 2 separate sound adjustments. Size of board: 2.5" x 2.75". Operates from one 9V battery (not included). Complete with all parts, speaker, PC board and instructions. Skill Level 2.