This electric mattress cover is excellent in all respects except three:
1. Contrary to the seller's representations, it's not 100% cotton - as stated on the little fabric tag sewn onto the mattress cover, the very thin top layer of fabric is cotton, but all the inner padding is polyester.
2. The two controllers have a major design flaw - if you set them to timer mode, so that the heat switches off after a pre-set interval, then when they do switch off the controller starts flashing rapidly with a bright blue light, which does an on/off cycle at least once per second - and which does not turn off until you manually switch the controller to OFF. So, if you're someone who would be happy to be woken up in the middle of the night by the strobe effect of your whole bedroom flicking with constant blue flashes like a night-club, then you'll find this mattress cover ideal. For the rest of us however this is a serious and completely pointless drawback, and makes you ask the question "What on earth were they thinking?"
3. The heating element doesn't cover the bottom 20 cm of the mattress cover, so it is useless for warming feet, which are in fact the coldest part of the body and most in need of the mattress cover.
After three rounds of correspondence, the seller (Direct Sales) reluctantly agreed to accept return of the mattress cover and made a refund.
Other than the above, the mattress cover heats up fast and hot, and is generally easy to use.