Heres a great item to protect your Nocpix RICO 3 diopter Lens (eye side). If you dont like to run the rubber eye cup it is imperative to protect the diopter lens from dirt, and smudges that can effect your shot. This is the correct Butler Creek Cap to fit the diopter lens.
If you shoot the Rico 3 without its rubber eyecup, a cap is simple protection for a lens that is otherwise bare. A smudged diopter lens blurs the display, and wiping it in the dark with a shirt sleeve rarely helps. This cap is sized for the Rico 3, so it fits right.
Both protect the glass. A cover can mean a full-length wrap or a flip lid, while a cap fits over just one end, like this one over the Rico 3's eye-side lens. On a thermal, the eye side matters because that is the lens your eye looks through to see the display.