Buzzer Sounder 3 Tone 12 V Horn 6 - 15 Volt Alarm Loud Piezo 39 x 22mm Leads x 1

If the green and yellow wires are connected together a two-tone siren sound is produced; if the green and orange wires are connected together the unit emits a pulsed tone, and if all wires are left unconnected, the output is a continuous tone.