A solid bit of protection for the Insta360 X5 that does not wreck image quality. It is a 9H tempered optical glass guard made for the X5, with a twist-lock bayonet fitting, and it is multi-coated with oleophobic and hydrophobic layers, with over 99% light transmission. The camera recognises Lens Guard Mode, adjusts stitching accordingly, and there is a notch so the microphone stays clear.Fitting took seconds. Line up the marks, give it a firm twist, and it locks with a positive click. It stayed put on a bumpy ride on the bike, and a tug test did not shift it. Video looks clean and sharp, with colours tracking as expected. Stills are a touch softer at the edges, and I did notice a little extra flare shooting into low winter sun. On first power-up I caught a fleeting internal reflection, then the X5 switched modes and it vanished. Stitch lines are tidy in daylight. In very low light I can spot a faint seam. The coating shrugs off fingerprints, one wipe and it is sorted. My rubber hood still fits over it.At £29.99 it is not cheap, but it is far cheaper than repairing a lens. The build is solid, the mount is secure, and the optical trade-offs are small if you shoot mostly video. Basic protection though not the cheapest.