I'm looking for a bike ringer to install on glass carts for work

We have these giant carts, and it's difficult to see around them, so I want to put ringers on them. I can't seem to find a ringer. There are LOTS of bells on Amazon and such, but I can't seem to find a ringer (bbbbrrrriiiinnnnggggg bbbbbrrrrriiinnngggg).

Eh?