The Spark has all the technology you would expect to find on an adults goggle but downsized to keep young eyes protected. The frame is Over the Glasses compatible for those who wear prescription eyewear.Lens: Golden eye VLT: 24% (CAT 2) Size: Youth - Small Lens Shape: CylindricalLensGolden eye – With a 24% VLT this lens is most suited for cloudy/overcast light conditions.Visual Light Transmission (VLT) refers to the amount of light that penetrates a lens. A low percentage means less light passes through and a higher percentage lets an increased amount of light through. A lens with a lower VLT rating is better for bright conditions, where as one with a higher VLT is more suited for overcast and snowy days.