A jumper offers a supported, elevated seat for baby where he or she can touch the floor with his or her feet and push off the ground in a jumping motion. Doorway jumpers require being attached to a doorway for support. Some jumpers also include a tray with toys and activities. Also called: Jenny Jump Up®, Johnny Jump Up® (Jenny Jump Up® and Johnny Jump Up® are registered trademarks of Evenflo and refer to their brand of doorway jumper)