Solid acrylic dome prefocuses and magnifies the image by a factor of 4. The base of the dome is slightly concave to resist scratches. Ideal for calcifications, lesions, subtle tissue distortions, film quality control and slides. A felt lined base and flannel bag are provided. Acrylic dome magnifiers are also available without the wooden base as a 2.5" diameter tethered unit to help prevent loss. A larger magnifier 3.5". diameter comes with neither tether nor base. All units magnify 4X.