The GUNNAR Cruz Computer Glasses are designed to help reduce eyestrain and fatigue caused by blue light emissions and extended viewing periods. Ideal for narrow faces, they are made with a flexible nylon frame, wide format lenses, a curved nose rest for even weight distribution, and 5-barrel hinges for durability. The Cruz frame style is recommended for ages 12 and up. Amber Lens Tint BLPF (Blue Light Protection Factor) is a rating for how well the lens protects your eye against artificial blue light. Like SPF (Sun Protection Factor) in suntan lotion, the higher the number, the more effective. The Amber lens tint offers optimal protection and performance and a BLPF rating of 65.