Easily attach these clip-on magnifying glasses to the brim of your hat and start tying flies. Clear acrylic lenses deliver a sharp, distortion-free view. They are available in 1.75X that’s equivalent to a +3.00 diopter, or a 2X that’s equivalent to a +4.00 diopter. Protective soft case included. Available: 4 Diopter, 3 Diopter.