See Better Headband Magnifying Visor has many of the features of more expensive magnifiers.
The hands free magnifying glass visor has two interchangeable magnifier plates, provide powers of 1.8x and2.3x. Used in conjunction with extra power lens (as illustrated) 3.7x and 4.8x can be achieved. Hands free visor magnifier. See-Better Headband Magnifying Visor Magnifier additional features.