Do an advanced search using 219 820 32 26 and onehundred80 and you will find my post with the picture of the siren, the need for the M8 nut and the fact that it beeps. There is a lot of BS on these threads and a lot of it is outdated or simply wrong. There may be other sirens that beep and I am sure that there are, but the number I give is correct and BEEPS.