Optimatch 3D Glasses Virtual Reality Headset VR Box for 4.0&rdquo; to 6.0&rdquo; Smartphones with Adjustable Strap Optimatch 3D VR Glass with Adjustable Head Strap Belt provides Comfortable Wearing Experience Top Wheel for Sight Distance Adjustment, Forward & Backward Button for Focus Distance Adjustment (Area 20mm) and Left & Right Button for Object Distance Adjustment (Area 10mm) Equipped with Anti-blue Light Coating film, Optimatch 3D VR Glasses can reflect blue rays from your phones, to safeguard your eye sight Comfortable with all smartphone screen size from 4.0 inch to 6.0 inch; Use only in a safe environment Three-month Warranty and a Lifetime Service Guarantee