An apparatus for use in forming sheet material assemblages includes a pocket assembly having upper and lower grippers. The upper gripper is spaced a first distance from a sheet material support portion of the pocket assembly to engage an upper edge portion of a large cover section having a relatively large distance between a fold and an upper edge portion. The lower gripper is spaced a distance which is smaller than the first distance from the sheet material support portion of the pocket assembly to engage an upper edge portion of a small cover section having a relatively small distance between a fold and an upper edge portion of the cover section. Pressers are mounted on a movable side wall of the pocket assembly and are engagable with a side of a small cover section to press small the cover section toward the lower gripper.