Abstract: A display frame for holding a flat member includes a holding frame portion having a separable frame portion separably secured thereto in a manner permitting separation only by an authorized person having a special tool. The holding frame portion includes a slideway for receiving peripheral portions of a flat member and has a slideway entrance normally closed by the separable frame portion. The separable frame portion is separably secured to the holding frame portion by separable joints, at least one of which includes a locking member completely concealed within the frame and having a movable latch portion yieldably urged to a locked position, and being movable to a released position. A limited access opening through the frame near the locking member provides access to its latch portion with a special tool for moving same to its released position.