Do they have it in the form of the clay itself instead of a pill like bentonite?
I tried bentonite once, about twenty years ago or more. Actually over 22 years ago is when I tried it. If I remember, it was a liquid.
If you click the link, I believe it likes to a container of powder to buy. There are other links from there to tablets.
If I'm not incorrect, when someone says bentonite, they mean the sodium based cooked bentonite. When it's written as terramin, it's the calcium based raw bentonite. I hope that helps.