Pumice

Larger chunks than wanted, but worked okay.

Website didn't say what size the chunks were. I was hoping for 1/4" minus, and left a note on my order to that effect (needed it ASAP, so didn't want to wait for a query and reply), but it was 1/4"-3/8", which is bigger than what I usually use (for potting soil), but it worked okay, except that it seems like the wild birds around here like to pick it out of the pots and leave it lying around. It must look like food to them, until they feel the texture! ;) Was a good deal, price-wise.

Nice and clean and great size. Plants love it.

Pumice Stone

The Pumice Stone works in my vegetable garden outside