LIFE TIME WARRANTY - 100% risk free to try, unsatisfied glasses can be refunded within 90 days of receiving. Customers will enjoy lifetime warranty( not man-made damage). In case of any problem happening, just contact us without any hesitation until you are satisfied. FRAME TECHNICAL CHARACTERISTICS - 1.Light weight Metal&Acetate frame for less pressure on your nose. 2.Replaceable lens to meet your reading glasses or sunglasses needs. 3.High wear-resistance, hard to break and 90 days return policy is another quality warranty. 4.Skin friendly without causing allergic reactions. LENS TECHNICAL CHARACTERISTICS - 1.Multifunctional coatings,like UV400 protection, anti scratch coatings. 2.Reasonable blocking rate. Firmoo computer glasses lens' blocking rate are designed at about 40% considering two reasons:Higher rate would cause color distortion, lower rate would not protect your eye effectively. NO MORE TIRED EYES - We are directly exposing to blue ray from phones, TVs and computer screens hours every day,please don't worry,Firmoo Computer Blue Light Blocking Glasses help you with discomfort like eye strain, migraine, blurred vision and hard to sleep. FRAME DESIGN CONCEPT - Based on choices of millions Firmoo fans,this glass is designed in Square with 4 types of frame color. Combining classic and modern style perfectly.Not only block blue light but release your style.Oversized Square Metal&Acetate frames are designed for American face type.