Our PortaBaby sheet measures 27" x 38", and fits most play yard mattresses, including Pack-N-Play and Co-sleeper brands. Play yard sheets are notoriously hard to use and uncomfortable. Our PortaBaby® play yard sheet is different. It works like a pillow case, with the opening on the long side. Remove the mattress from the play yard, slip it into our soft, durable sheet, and secure the hook-and-loop closures for an easy fit. Drop the mattress back in and you're done!