Where to find small magnifying loupes?

I've shared photos and updates with images of small loupes that are convenient for taking close up photos of grass and soil. For example:

- A convenient pocket loupe - 7x pocket loupe on a green - Ultradwarf bermudagrass tags after mowing - Angular sand on a bentgrass green

Many people have asked me where to get these? What you are looking for is a stand-type loupe, and these are not jewelers loupes, but instead are designed, as I understand,…