The only thing I ever swirl is the powder into the water before I put my magic little magnet in. Speed Stir FTW !!!!!
Eqbob, I assume they are speaking about the sample sizer.
The sample sizer is a metal thing that gets put into the vial, after you add the water sample, which insures that there is exactly 10 ml or 25 ml of water in the vial. There is a good picture of one here.