I like the look of this bell. It is very low profile so it doesn't "stick out" on my road bike.
Unfortunately, it's not very loud. I have a more traditional bell on my old-school MTB and that is loud. And the harder I push the lever the louder it is. With this one, the ringer is spring mounted and you pull it back and release. You can't vary the volume at all. It's all done by the spring. And, well, like I said, it's just not loud. I have to be nearly directly behind the person for them to hear me. And if they have headphones on, they won't hear me at all.
It also has some issues with its usage. To "ring the bell" you have to use your thumb to pull back a small spring-loaded plastic lever and release it to hit the bell. The problem is it twists very easily so that the primary striking surface gets turned away from the bell. So then you have to fiddle with it to straighten it. And if you're trying to alert someone to your presence, you don't really want to have to be fiddling with the bell.
I really wanted to like this bell as I really like how it looks. But I will be looking for an alternative.