Have used these "protection" panels on several client installs and will not be using again. Although good for covering buttons and preventing altering of settings, the Plexi used is far too brittle, with most of the ones I've ordered being broken or cracked in transport through no fault of the delivery company or packaging - I've even had the plexi shatter from a bad metal frame. Speaking of, the metal frame is feeble and bends easily.
I would suggest a vented or locking metal cover instead of these Plexi covers, unless you want to use them decorativly and can guaruntee there will be no "heavy" usage.