Hi Elderblaze,
Oops … I scanned the link without clicking it and thought it went to their latex/innerspring hybrid. Sorry.
There is more about the pros and cons of different types of mattress protectors in post #89 here. The Protect-A-Bed is one of the thin “membrane types” of protectors that would have little effect on the feel of the mattress, are “semi breathable” and waterproof, and don’t have the “crinkly” feel of the old style vinyl types of protectors (the membrane is a flexible polyurethane material). While I have seem a few complaints about most of these types of protectors (regardless of brand) … most people don’t seem to notice it at all.
I just called them and they told me that the MU5 code was still correct and “should” be working but if for some reason it didn’t then you can call them and they can give you the discount manually.
Phoenix