Abstract: A divider assembly for dividing adjacent stacks of sheets during stacking in a stacker mechanism including a tray, mechanism for moving the tray from a sheet receiving position to a sheet discharging position, and a pusher for discharging sheets from the tray in its sheet discharging position. The divider itself is positionable on the tray to separte sheets into separate adjacent stacks, and includes a relatively thin central core, with a plurality of flexible feet secured to the core and having free ends extending below the lower edge of the core. The divider also includes a hinge interconnecting the pair of flexible feet so that the feet with the hinge may be collapsed inwardly when the divider is withdrawn from between the adjacent stacks, thereby permitting easy withdrawal of the divider from between the stacks.