I bought some generic PC keyboard covers to protect my Apple keyboards when they're not being used, and they work great. I think we paid about $6 apiece for them at Office Depot. They're actual covers, not ergonomic key covers that allow you to type etc. Since it's only myself, or my gal Friday who are using the keyboards, and occasionally my wife, we don't treat them badly, eat/drink while working etc. It's just to protect them from dust and dirt when not in use, that's all.
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What's the difference between reality and fiction? Fiction has to make some sense.