The XP stands for Xtra lens Protection, and that's what you get: larger lenses for maximum coverage, clarity, and glare reduction. Includes a Reflex polarized lens and a SportFlex lens for low light conditions. Fits medium to extra-large profiles.100% UVA and UVB protection. Polarized Reflex lenses provide increased glare reduction and enhanced styling. Strong, lightweight frame. Cushinol padding at nose for superior comfort and stability. Mastoid Temple Grip for a secure fit behind the ears. Venting system enhances airflow to eliminate fog and moisture on lens. Toughest anti-scratch coating available. All Native lenses pass the ANSI Z80.3 test for impact. Includes SportFlex interchangeable non-polarized lens for low light conditions: 60% light transmission. Includes Optic Gear Kit: semi-rigid case, soft pouch, retainer strap, SportFlex lens. Charcoal frame: Silver Reflex lens for extremely bright sunlight with 10% light transmission. Asphalt frame: Copper Reflex lens for moderate to bright sunlight with 14% light transmission.