Lately I decided to upgrade and bought the Donegan OptiVisor with both the 2.75x and the 3.5x lenses. In addition I added two of their optiLoupes, one for each eye. This is by far a better tool than my previous ones.
I've tried all kind of optical solutions before: the loupes with and without the wire (wire from Bergeon, mind me). I own several of those from different manufacturers: Horotec, Bauch and Lomb, generic, you name it. I can't stand them!
I also ventured into the stereo microscope and the Donegan double-glass loupe which attaches to the glasses (with two lenses)...also a couple of different Chinese versions with different magnifications....also some sort of Chinese loupes that come in a frame like glasses. No success either!
Of all of those solutions, I believe the only ones that fit the bill for my style are the latest Donegan Optivisor: they are comfortable, -- not like my previous Chinese versions, second place in this "mini" review -- and they offer the magnification flexibility I need.
As a plus the Optivisor can be used with glasses, (the Chinese version too) which I will when my new ones are ready. One down side is for close work at high magnification you have to be careful since they tend to hit things around your bench if they are too close to your work...think mini bench, etc. I will probably buy the 2x or less magnification lenses in the future since sometimes it is all you need or...
My next one will be a round, lighted bench magnifier and see how it fares...
Hope this helps,
Cheers,
Bob
PS: The Donegan models of Optivisors include the LX model but those use plastic lenses. I passed on those although the price was attractive. The parts are interchangeable with the regular model using crystal lenses.