Thanks @johnny. Actually-- I referred to the Weber format only to provide a sense of the size. In actual fact I'm wondering how to reduce the heat on a very primitive grill (or pit) without a lid or vents. Sorry for the confusion. I have edited the question to clarify.

Thanks @hobodave. Do you know what brands it is sold under?

Isn't this a recipe-question-no-no? I love the question but just trying to understand. Thanks.