They aren't really for holding anything in particular, they are kind of a general purpose clamp for holding whatever you want held on a stand or over a flame or such. Test tubes, flasks, (the ones for beakers have bigger fingers) distillation apparatus .....
It is surprising how hard it is to reach 90 proof....
*Cough*
>sugar and potassium chloride
Waste of perfecly good sugar, sugar is for fermenting...-P