This mattress delivers on quality of material. Standard cal king sheets work great. It’s definitely ultra firm without being hard as a rock. You don’t sink into mattress, which is great. We are both 6ft-6’5 ft tall and fit comfortably width wise and especially length wise. We’ve had it for a couple weeks now and it’s held up like a champ. I naturally run hot; the mattress temperature stays neutral. Would recommend.