I've got that same bell on my bike - it was on there when I bought it and I had not freakin' idea what is was

In fairness my more cycle-savvy boyfriend was equally perplexed.
I think I'm going to have to move it slightly cos it's just out of reach and most times I want to give someone a "ting!" by the time I've located it the moment has passed. It's a nice bell actually cos it's the equivalent of a polite cough rather than an "OI!!!" so you feel fairly safe using it without risk of causing pedestrian rage.
Most of the time I only want to say "hey, just want to be sure you know I'm here" rather than "get out of the fucking way you dozy cunt!" (well ok I might be *thinking* the latter but only want to communicate the former

)