Ultra-light, Cat 3, Sunglasses ideal for Fishing, Driving, Hiking, Camping & Outdoor Sports at Hugely Discounted price. Category 3 is one of the five internationally recognised lens darkness levels defined by the ISO 8980 standard. While Category 0 lenses are clear or lightly tinted for indoor use, and Category 4 lenses are too dark for driving, Category 3 sunglasses are designed for bright outdoor light, balancing visual comfort and safe visibility.