Tractor Supply Corp offers crushed Walnut shells @ $12.99/10 Lbs.: they offer Corase or Fine grit; I assume coarse is best (won't stick in flash holes), The coarse grit is 12/20 mesh; the fine is 35/60 mesh....it is used as blasting media and the mesh is important for its application. They also offer a medium grit 18/40 mesh but it costs more. I would guess it's better than lizard bedding as the later is not screened and one would get particles of all different sizes....can anyone offer me some advice before I buy ten lbs please?