See Better Head Strap Visor Magnifier has many of the features of
more expensive magnifiers.
The hands free head strap visor magnifier has two interchangeable magnifier plates, provide powers
of 1.8x and 2.3x. Used in conjunction with extra power lens (as illustrated) 3.7x and 4.8x
can be achieved. See-Better
Head Strap Visor Magnifier Features.