DESCRIPTION: Made to fit Sleep Number beds. This outer shell is complete with pillow top tailoring. Sewn slots for dual air hoses. This complete outer shell is made to fit any Sleep Number Bed that has only one zipper that goes around your mattress. If your mattress has two separate zippers that go around, you would need the Box Top Shell. This replacement cover features the same YKK zipper (5cnu) that has been used on Sleep Number beds during this time period. Not only is this shell made in the U.S.A., but all components are as well. We use only the best fabrics, foams, upholstery threads and padding. This complete shell is specifically designed to fit Sleep Number beds. We guarantee a snug fit, just like the original. Questions? Email or Call one of our experienced craftspeople who sews these covers right here on site! Note: Magic Sleeper makes after market covers for Sleep Number brand beds and we are not affiliated with Select Comfort or Sleep Number in any way. MEASURING HEIGHT: Best Way to Measure Shell Height. There are two ways you can measure the shell height. As shown in the picture above you can measure the side of your border from top to bottom excluding the piping. Depending on the age of the mattress, sometimes it is hard to get an accurate measurement because the sides might start to impress over time. A Second way of finding out what size shell you need is to start by measuring the height of your foam side rails. You want to measure a spot where there is the least wear and tear ( normally at the head or foot). Then you want to measure any additional comfort layers you may have that sits on top. From there you would add the total height of them added together ( Foam rails Any comfort layers on top ) And that will give you the height of the shell that you would need to order!