Hi Buckeye_Guy,
Outside of SallyS’ comments you can see some comments from Cheryl at Cozy Pure about their protector in post #12 here and some feedback about them from forum members here and here and here and here.
I’m not sure if you are asking about the covers on the Tempurpedic mattresses or their mattress protector. The type of covers they use for their mattresses varies from mattress to mattress but they don’t specify the fabric they use in the Cloud Luxe except to say that it’s cool to the touch and moisture wicking. Tempurepedic also doesn’t specify the material they use for their mattress protector except to say it’s a “high tech” fabric that is waterproof, stretchy, and breathable (similar to “membrane” type protectors). There is also some information about it here (click overview) but it only mentions the cotton terry not the specifics of the “weave lock” material that would give it it’s water resistent/waterproof properties. If a fabric is waterproof or “almost” waterproof then it will also restrict airflow to some degree which for some people will mean it can also sleep warmer.
Phoenix