Here's the description from the product page: Cut-away base for easy retouching. Twin aspheric focusing lenses. Clear base for maximum illumination of image. Comes with lens cap for protection of optics when not in use.
Lens Diameter: 1-1/4”
Viewing Area: 1-1/4” diam.
Overall Size: 2-3/4" diam. x 2-1/2"