Comfort Beddings Present Split King Sheets.These Split king sheets are designed for use with split king mattresses, which consist of two separate mattresses. These mattresses are often used with adjustable bed frames, allowing each person to customize their side of the bed for personalized comfort. Split king sheets typically come in a set that includes one fitted sheet, and a single flat sheet that covers both mattresses. Additionally, the set usually includes two pillowcases, though this can vary depending on the manufacturer.