Can a mattress rest directly on the Bear Adjustable Flex Bed?

Yes. The Bear Adjustable Flex Bed can be used in lieu of a bed frame, foundation, or box spring. The Bear Adjustable Base can fit inside a sleigh bed or common four-post bed. No part of the frame moves downwards, which allows you to remove the legs and rest the adjustable frame itself on the floor or on top of a platform base.