A:
Diameter and length.
I strongly recommend slip floats and good slip knots.
When minnow fishing for crappie and walleye, I always use a #6 hook and a split-shot sinker a little ways up from my hook.
I've found that the bigger floats are excellent too for big or open water.
I can put the appropriate weight on below, and I have a rig that is just right, and hair triggered.
Most of my slip floats are smaller or medium size.
They're All Good.
A recommended product, honestly.
Good luck.