Binocular Headband Magnifier, basic, 2X Mag.  Ref: binocmag-S3

I would recommend this one if you require a long working distance and reasonable magnification (which you will never get with simpler magnifiers) AND if you really can't justify spending over £100.00 - this one IS remarkably good value for money. The optical quality is OK, quite clear in the middle, but quite wobbly around the edges, that's the quality you get for this money. But the advantage IS that you get a relatively high magnification AND long working distance.