9mm Electromagnetic Buzzer: 30Ohm, 3-7V, Side Opening

via Pololu
$3.54
SKU PL-1484

Frequency response of the 9mm Electromagnetic Buzzer: 30Ω, 3-7V, Side Opening.

We also carry a similar buzzer with a top opening.

For an example buzzer circuit, see the schematic for the A-Star 32U4 Prime.