Don't buy Sleep Number sheets!
I bought split king sheets to fit my Sleep Number bed, replacing the $250 "special" sheets we were sold that discolored and wrinkled. We were told that they were "the only sheets that will fit to be a split king sheets that would fit the bed" and that was not true.
The new twin XLsheets that I purchased from Bare Home are great value great price and wonderful to sleep on. They fit the bed perfectly. There is a wide range of colors to choose from and delivery was quick and without a hitch.
Whatever you do don't buy Sleep Number sheets! The beds are great, the sheets are unacceptable.