"The Viso-lux 2636-11's rectangular, big field lens is perfect for reading and writing. The Viso-lux 2636-11 features an aspheric PXM® featherweight lens with cera-tec® coating, an open base for writing, and a clear, bright viewing base made of translucent plastic.
The 2636-11 has a 7D aspheric lens with a ""snap-on"" 4D lens attached underneath. The 4D ""snap-on"" lens may be readily removed for tasks like handwriting."
