32mm (1 1/4 inch) button parts
The 32mm is the smallest possible variant with a handy built-in safety pin at the back. Do you want to work fast (afterwards no pinning of the buttons like with the 25mm) and still a small size then the 32mm is what you're looking for. Faster and firmer than the 25mm!
Just like the 25mm very popular with bands and as an accessory of discrete size.