Hi Nene1957,
There is more about the pros and cons of different types of mattress protectors in post #89 here. The Luna is one of the “thin membrane” type of mattress protectors that have a “semi breathable” waterproof membrane.
The “argument” is that it’s mainly for hygienic and health reasons to protect the people that handle the mattress. A stain can also indicate that moisture or liquids have entered the mattress which can damage or degrade some types of foam or other materials and this type of damage is considered to be “abuse” and also isn’t covered by a warranty.
Assuming that you are purchasing a Select Foam mattress … I hope you are happy with it as well … and congratulations on your new mattress
I’m looking forward to your comments and feedback once you’ve received it and have had the chance to sleep on it for a bit.
They are also one of the few manufacturers that allow a return if there is a relatively minor stain on a mattress (see post #2 here) but of course it’s always a good idea to prevent any stains instead of hoping that any stain will be “minor enough” to still be covered by a warranty.
Phoenix
NOTE ADDED: Because of ongoing customer service issues and delays Select Foam’s membership has been terminated and I would read the warning here before considering them.