Split Top King Sheet Set (Flex) vs Split Top King Sheets 600 Thread Count

Buy the cotton set (B) if you want a breathable, natural-fiber sheet for a split-top adjustable king and your mattress is up to 18 inches deep. Buy the microfiber set (A) if you want wrinkle resistance, a softer out-of-the-box feel, and a much larger track record of owner ratings. B has the better fiber and deeper pocket with a 32-inch split and six corner pockets; A counters with a fully elasticized edge, hypoallergenic finish and 6,477 ratings at 4.5. Owners of B call it a good fit for Sleep Number beds but some find it scratchy at first; A's microfiber is easy care but less breathable than cotton.

• Choose the 1800 Series microfiber set if you want wrinkle-resistant, low-effort sheets that fit mattresses up to 16 inches and you value a long record of owner feedback.
• Choose the 600 thread count cotton set if you want breathable long-staple cotton, an 18-inch pocket and a 32-inch top split built for Sleep Number-style adjustable beds.