Pandora Round Memory Foam Mattress 87"diameter. Our High Quality Pandora-Round Memory Foam Mattress is 87 inches in diameter,10 Inches thick- it has the support base layer of 7 inches of high density foam core and 3 inches of 4.6 lbs Visco Memory Foam. Memory foam is resistant to dust mites and is naturally antimicrobial, Allergen-resistant, removable and washable cover with non-skid bottom. Ship Via Fed-Ex Ground.