This is the optical quality, single vision MV Optical Model 31 with CR39 optical reading lenses. The larger, slightly squared, rectangular frame is a classic take on the intellectual, studious and smart wearer. This has adjustable hanging nose pads and spring hinged temples, assuring a comfortable fit on a wide variety of head sizes. The slightly larger lens and bridge size make this a perfect fit for most male head shapes. Model 31, by the experts at Multi-View Optical are a very high end, optical quality acetate frame sized for an average (unisex) head size. These single vision CR39 acrylic lens reading glasses are available in any power from +1.0 up to a +2.0. A CR39 optical lens is the latest in reading lens technology: Impact Resistant, Thin Light Weight, scratch resistant and includes 100% UV protection. Style 30 has a smooth acetate finish with spring hinged temples. Available in black or brown. Includes a clam shell design hard protective case.. Style 31 is sized for an average male head size. Here's the optical sizing scoop on Style 30: Lens: 54mm, Bridge: 18mm, Temple: 140mm