Abstract: Display panels for ready assembly and disassembly to form walls or shelves particularly suitable for trade show displays and the like, have sections of elongated cylindrical metal tubing having a first channel attached to edges of the panels to be used in the display. An internal expandable open groove is provided in the metal tubing for receiving a flat connecting member with ribs on opposite edges thereof to snap-fit into and engage the groove in the metal tubing. Connecting members then are used to interconnect the sections of tubing attached to adjacent edges of different panels to permit assembly and disassembly of the various panels without the use of any tools, while providing a rigid display section.

Abstract: A hinge for building doors and windows is recessed into the jamb when the door or window is closed and includes pivotally interconnected 4-bar link mechanisms which function to swing the end face of the door completely out of the way of the inside cross-section of the door opening when the door is opened from an angle of 90.degree. to substantially a full 180.degree. nearly parallel to the wall in which the door jamb is located.

Abstract: A door frame assembly is made of first and second aluminum extrusions which may be placed in a door opening in wall after the wall has been completely finished. The structure of the frame assembly inherently compensates for variations in wall thicknss and dimensional errors in the door opening dimensions. Steel anchor plates are fastened to the wall in the door frame opening and the assembly is attached to the anchor plates. Once the completed assembly is in place, all of the attaching members are concealed from view.