I've been using one of those for a few months. Doesn't work on gravel surfaces. Only so-so on soft sand type surfaces... worse if it's recently rained as it tends to drop shelss if you push down too hard. Works very well on hard surfaces like concrete, hard packed earth, grass. I may not be able to use it all the time, but when I can it works quickly and easily and saves my back (and my wifes) from bending over repetitiously. Can get a lot of shells quickly as long as you recognize that some surfaces are more conducive to its use than others.
