Hammer Headset Spacer Bell, Brassbellhed
The diameter of the bell is 45mm (1-3/4") so it's like a mini hammer bell.
It'll work on both 1" and 1-1/8" headsets, with the included 1/16" thick shim. You just need to make sure you got at least one cm of spacer space in 'tween the locknut and top cup (see pix below) since the bell spacer mount is 9 mm tall. You'll have to take your bike apart some in order to install the bell, so, if you don't know how to do that, get a grease monkey bike friend to teach you how to do it - it's simple, really, but you do need a few special bike tools and a little training to put everything back together right.
Mounting as shown in the pix (on the left, lever in the front) is only one way of many. There isn't a Best and Only One Way to mount this bell. Try it a a few different ways and see what works best for you.