RS PRO Panel Mount Buzzer, 24 V dc, IP40, DC

If you need a simple and effective buzzer, this one from RS PRO could be just the thing. It has a sound intensity of 80 dB at 0.1 metres, so it's easy to hear over most ambient noise.

The buzzer's housing is made of polycarbonate material, which offers a good level of strength and resistance to wear, so it will last for a long time. This product also has an IP40 (Ingress Protection) rating, meaning it's protected from wires and small tools greater than 1 millimetre.
A buzzer like this one is often used on aircraft and boat instrument panels. It has been stringently tested for quality and safety by engineers.