@Bamboozle, which focal length works best at the bench?
It's a working distance thing so you have sit down at your bench and figure out how far away your eyes are from your work when you are seated COMFORTABLY, not leaning in.
I also have a second pair for "leaning in" with a shorter focal distance when I tie the REALLY tiny stuff and feel I need more magnification. OptiVisor also sells an add on loop that beefs thing up even more if you want that.
IF you wear eyeglasses, you may have wear them down around you nose to see things lying on your bench but not IN your vise, because you may find wearing your glasses in conjunction with the head loop screws up your working distance.
It's not as complicated as I am making it sound, I just want to give you an idea how to choose & what to expect.
The great thing about a head loop versus a desktop magnifier is you won't whack it with your hand when winding materials like can happen with a magnifying glass and you can use them for a lot of other stuff.