Welcome to the forum. I am assuming this is for a bed that top half slides up over the bottom half when retracted. If so household style Queen bedding works fine on ours. If you get the Deep Corner Pockets style it works even better... We added a 2 inch memory foam topper with a deep pocket mattress cover and it all stays on when the bed slide is retracted and extended.
Wayne and Christine
2021 R-Pod RP-192 with OEM Solar
2020 Ford Expedition Platinum 4X4, 3.5L EcoBoost, 9,200# Heavy Duty Trailer Tow Package with 1524# Payload