Warning Buzzer & Chime (1) Piezoelectric Piezo Ceramic Wafer Plate Dia 12MM, 15MM, 18MM, 20MM, 27MM, 35MM, 50MM, copper, bonding wire, For Buzzer Loudspeake (2) Piezoelectric Piezo Ceramic Wafer Plate Dia 35MM, 50MM. Copper, For Buzzer Loudspeake