I would definitely recommend the Bausch and Lomb folding pocket 3 lens magnifier. It is very useful for part inspection and is flexible with multiple magnification levels.

This is a very handy little magnifier - just right for viewing bugs or small items in the field. It is lightweight and fits easily into any pocket. The focal range is versatile enough to satisfy just about anyone, though the lenses themselves are somewhat on the small side. My biggest complaints (and these are relatively minor) are that #1 - there is no hole or device to allow for the attachment of a lanyard. It would be nice to have some way to hang it round the neck or put it on a belt clip where it would be handier than digging it out of a pocket or bag. (Less likely to be lost that way too!) #2 - it really needs a small outer case or bag of some kind to keep dust off the lenses when not in use. But it is sturdy, well made and does exactly what it is made to do. #3 - This is very minor, but the small size of the magnifier makes it easy to lose if dropped (especially in a tall grass field!) so having a housing in some bright color (Orange?) might make it easier to find. But, overall ...
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