A binder mechanism (20) includes a rotatable support (110) having ring segments that can be locked in a closed configuration. The binder mechanism includes a horizontal and/or a flush mounted push button (70) that opens and/or unlocks the rotatable support. The push button acts on a ramped slider (90, 102) that causes the rotatable support to rotate open. An over-center arrangement (120, 114) aids in maintaining the binder mechanism closed or opened.
