This is one replacement lens for LayerLens for the GoPro 3 & 4. This lens is a 2mm thick, high quality, photo grade, hard and anti-reflective ("AR") coated lens with an anti-smudge coating on the viewing side. This lens has AR coating applied to both sides of the lens to ensure high light pass-through and minimal external and internal reflections. Handle with care and only clean with a cleaning solution appropriate for AR coated lenses and a microfiber cloth. Do not use ammonia based cleaning agents such as Windex as it will destroy the AR coating. Made in the USA.