(Image credit: Future)The good news is that once your mattress is unboxed, it's pretty much ready to sleep on — and you'll appreciate the lie down after maneuvering the thing.Normally, I can dismiss a difficult unboxing process. After all, mattresses in a box are never going to be light and once they're out of the packaging, the job is done.Get instant access to breaking news, the hottest reviews, great deals and helpful tips.However, the Plank Firm Luxe is a double-sided mattress, which means you don't just unbox it and leave it. Every so often you're going to want to flip this bed to enjoy the other side. By myself, I simply can't do it. That means either missing out on one half of the bed, or begging the Tom's Guide fitness team for advice on building your 'mattress flipping' muscles.The firm feel delivers incredible support to ease back painsUnboxing the Plank Firm Luxe might have done a number on my back but the mattress itself is great at soothing aches and pains. The firm feel keeps your whole body lifted — whichever of the dual sides you're sleeping on — to reduce strain on your spine.As a front sleeper, I'm used to beds causing tension in my lower back (this unusual sleep position works against the natural curve of the spine.) However, the Plank Firm Luxe lifts everything from my shoulder down, holding me in comfortable alignment. That's the kind of feature I look for in all the best mattresses for stomach sleepers.