I plan on running them when I switch tires this summer. They offer two styles of beads: the small which are the size of sprinkles for cookies/cakes/etc, and then some larger ones that are designed for aggressive/offroad tires. The larger beads have to be installed when the tire is being mounted because they are too big to fit through the valve stem. They also tend to "clump" less if they would happen to get excessive moisture in the tire.
Both sizes function the same and you can use either size - just need to get the proper amount (oz.) for your tire size.
The smaller beads can be installed through the valve stem UNLESS you have TPMS. If you have TPMS you will have to break a bead and pour them in.
Here's a good demonstration of how well they work.