MICROFIBER: These are the softest type of microfiber bed sheets we have created. Super soft with a light feel. Not crisp like cotton. If you're accustomed to cotton sheets and you've never tried microfiber sheets we recommend you at least give these a try. They're even softer than Cotton! EXTRA DEEP POCKET SHEETS / EXTRA DEEP FITTED SHEETS: These bed sheets are for very deep pocket mattresses. They fit any mattress with pockets that are 18, 20, 21, 22 and 24 inches deep mattresses. There's a stretchable elastic around the extra deep fitted sheet which stretches for a nice tug around your mattress. Perfect for extra tall & large mattresses. Rest assured these oversized sheets will stay on tight & stay in place! GREAT FOR DOUBLE PILLOW TOP MATTRESS: These bed sheets are perfect for mattresses with a 3 inch or 4 inch topper on top, memory foam toppers, big mattress pads, pillowtops, foam toppers, big foam toppers, pillow top mattresses and memoryfoam. These sheets will not come off and they will stay on!