The percentage VLT is the amount of light being let through by the lens. The lower the VLT percentage equates to less light coming through – perfect for bright conditions. The higher the VLT percentage is, the more light the lens allows through, enhancing your clarity in low light or variable conditions.
Low Light lenses will allow somewhere between 60-90% VLT and generally will be Rose, Yellow or Blue tints. These colour lenses are for those whiteout days as they have the highest VLT percentages.
Clear lenses are excellent for night-time skiing/riding but do not add enough extra contrast through the lens for daytime overcast days. Variable tints are extremely versatile and can be worn in any weather condition. They will allow for around 20-40% VLT through the lens, perfect if you are unsure of what the weather conditions will be on the slopes.
Some lenses are far better for sunny conditions, allowing less VLT through the lens and cutting out glare. These may range from 5-20% VLT and often come in dark grey, black, red or gold and will usually have a mirrored finish. There's a huge middle range between these highlight and lowlight lenses, and that's where a good all-around lens comes in.