1.Washable and durable, the surface of these patches are blue, nice color for kids' glasses and the side wing will help to block side light. 2.NO IRRITATION: A hole that can be fixed on the glasses,convenient to use and no irration to skin. 3.LONG TERM FOR USING: It is reuseble,not disposable.save your money !! 4.Careful design make it easy to assembly and disassembly Training the lazy eye to work properly so that vision can develop correctly. 5.MONEY BACK GUARANTEE:If you are not happy with our product ,feel free to contact us .100% money back or replacement!