I like that model SOG demonstrated.
One of my very favorite stores in the capital city, is Lee Valley Tools, who are primarily a wood workers dream store.
But along with wood working, Mr.Lee found that many of us also enjoy gardening so they also carry an awesome selection of implements for our growing delight. Over the years, they have carried a few different monocular models.
The one they carry now, I have my eye on. Literally & figuratively. ;-)
While the low cost may suggest otherwise, this is actually a surprisingly good-quality microscope. Compact and portable, it has a bright LED bulb to illuminate objects, and a 20-40X zoom lens that is easy to focus.
Useful for inspecting anything from tool edges to houseplant pests, or simply for satisfying your curiosity about things too small to see with the naked eye. It also makes an excellent introductory microscope for children.
It stands 4-1/2" tall with the slide-holder base attached (can also be used without the base). Two mounting slides and three button-cell batteries included. Color may vary. A wonderful stocking stuffer.
My buddy has this one, he picked up a few months ago, and it is handy with the iPhone camera.
These type of microscopic devices have been around for a very long time.