I ordered a pair of these from the USA to try myself and was so impressed I decided to order them to sell on our site.
I first bought these as an alternative to the clip on magnifiers , which are good but need an o-ring and care in use to prevent loss of the magnifier if it falls out of the retaining clip.
The hat-eyes needs a longish peaked cap to function well as this gives enough space for it to fold up properly under the peak. The quality of the lenses is excellent and the double hinged system allows lens position adjustment. Optically a step up from our cheaper product and makes tying on flies and tying leaders almost a pleasure! Well supported with a stainless steel frame so corrosion is not a worry.
We stock HatEyes in a three magnifications. From MagEyes:
The quality of the MagEyes lens easily distinguishes it from others. The costly precision-controlled manufacturing process produces clear optic-grade acrylic dual-lenses, free of distortion or irregularities.