Megatronix NBS6 Super Loud 12Volt 120db 20Watt Six Tone Mini Car Alarm Siren With Rechargeable Battery Backup Super loud six tone electronic mini siren with rechargeable battery backup DC 6V - 12V 120db 20Watt Positive and negative trigger inputs Dimensions: 2.5"L x 2.25"W x 3"H