From Eschenbach:
Solar Shield® absorptive filters are fits-over eyewear that improve contrast and reduce glare and they are available in five lens tints: yellow, orange, amber, gray and plum. They are available in two frame sizes: Small and Large. The small frame size will fit over prescription eyewear up to 5 1/2"w x 1 5/8"h (142mm x 42mm) and can also be worn alone as well. The Large frame size fits over prescription frames up to 6"w x 2"h (153mm x 49mm).
Solar Shield® filters block 100% of harmful UVA & UVB light and the plum lens is polycarbonate and provides medium blue light filtering which is ideal for contrast enhancement and improvement in visual acuity. It blocks 100% visible light up to 521nm.
