A third party vendor will come up with a cap, maybe Acxmaxx which came up a filter and glass screen protector for the IV. Then there is the Susie solution that may cost almost nothing that comes from the kitchen or a really good hardware store - google metal caps and see what you come up with after you measure the diameter of the lens. As far as losing you can attach the cap via cord thru the extra strap eyelet. I like the Susie solution the best.