Smoke Transparency -The smoke back shows off the natural elegance of your phone Screen Protection - 0.77 mm raised lip along the screen edge to keep your screen away from scratches and contact with flat surfaces Reinforced Protection - High quality case protects against scratches, bumps, and more Screen Protector Compatible - This case was specifically designed to fit most screen protectors, Anti-Stick Prevention - The microdot design prevents sticking and an uneven fit with your phone and the case, Wireless Charging Compatible - Easy to use with case with wireless charging, 6 Months Manufacturer's Warranty Yellowing of polymer materials is mainly due to a variety of degradation reactions (thermal, photo-oxidation, radiation, oxidation degradation's). These reactions are chemical in nature, so they are irreversible."yellowing" is just an aesthetic problem and there is no application functional failures.