I would be REALLY into these if they made them with caliber designations written on the inside/outside. I have ARs in 6.5G, .300BLK, 7.62x39 and .223/5.56 and I have purchased traditional dust covers with caliber markings to put on each. However, the process of removing the existing dust cover and replacing it without removing the hand guard and (sometimes) barrel nut is a PITA. This is a great solution.
Times sure change. When some gun manufacturers started putting plastic on guns, people hated it. The aftermarket soon came up with metal replacements to upgrade if the gun was popular enough. Here we have a plastic part, replacing a metal part being considered an upgrade. Different times.