LayerLens ended up ripping the rubbery ring around the lens off, so this Flanged ring is a perfect fit (might need to sand off the elephant feet). It provides some light shielding and protection to your GoPro lens. The one picture shows the hit it took after a bad crash. The tight fit is needed to prevent it from popping off. No adhesive material is needed. There is also a normal ring that is similar in size to the original. I use it when I want to use another layer lens.The fit is intended to be very tight. sand down the inside edge near the lens until it fits over the small stubs on the GoPro.