Greenfig,
I wonder if that stock photo shows sifted or unsifted Floor Dry. Those particles in the image actually look pretty big (i.e. a good size) to me. The equivalent calcined clay product I get from Advanced Auto Parts has a much larger range of sizes, including very small pieces and some powder, that really should be sifted out.
Also, note that DE (diatomaceous earth) IS different than the calcined clay used in Napa floor dry and turface and such...
Cheers,
Jim