A cabinet which is demountable. Walls (11) of the cabinet (10) are joined edge to edge by join elements (12). At the apex (15) of each intersection of the walls there is a retainer (14). The retainers (14) prevent the joiner elements from being removed. One of the retainers which is the last to be installed when the cabinet is assembled is lockable. The retainer (16) needs to be unlocked and removed before any of the joiner elements (12) and retainer elements (14) can be removed to disassemble the cabinet.

A panel joining device formed in the manner of an extrusion which in section takes the form of two intersecting planes where the longitudinal one edge of each plane includes a vertically projecting first ridge. A second ridge is formed on the opposite face of each plane, across the intersection, such that the first ridge of one plane is directed towards the second ridge projection of the second plane. The first and second ridges are furthermore disposed to engage a first and second groove respectively formed on the face and in the edge surface of a panel to be joined with a similarly grooved other panel by the joining device.

This modular furniture is formed from components of varying size and configuration which can be connected together to form different furniture combinations. Each component includes two pairs of opposed panels, which are provided with chamfered side edges and adjacent grooves. The panels are interconnected by corner-forming rails having angularly related legs terminating in elongate lips which are received within associated panel grooves to hold the chamfered edges of the panels together in a box-like formation. The legs of the rails provide cooperating outstanding bearing faces spaced from the panels, and adjacent panels of corresponding components are connected by fasteners tending to draw the panels toward each other. The components can be modified to be fitted with individual covers.

A kit composed of a plurality of parts capable of being assembled without tools into a cubical cabinet includes four wall panels made of injection molded plastic which may be joined together to form four sides of a six sided cubical cabinet. Each of the four wall panels is formed with connecting devices extending along two of the sides of the panels with the connecting devices of each panel engaging the connect-devices of another panel to join the panels together. The panels in the kit also include securing devices formed on the same sides of the panels as the connecting devices. A torsionally rigid rear panel is adapted to engage each of the four assembled wall panels to form a real wall for the cubical cabinet and the kit is also provided with a front closure member which may be assembled to form the front of the cabinet.

At an outlet of a heating, ventilating or air conditioning system air passes from the ducting through a plenum chamber, a damper provided with a set of blades which are movable between open and closed positions and a diffuser which directs the air in a desired direction. The plenum chamber is provided with internal vanes which act to guide a flow of air through the chamber between its inlet and outlet. The damper defines a plurality of predetermined blade positions between the open and closed positions and a resilient finger and teeth for retaining the blades in a selected one of said predetermined positions. The damper has a frame comprising a plurality of discrete frame elements interconnected at each corner joint of the frame by a friction fit pin passing through interdigitated projections on the frame elements. The diffuser is formed as a plurality of concentric portions which are each integrally formed with cooperating snap-fitting connections enabling the portions to be interconnected to form a complete diffuser. The blades for the damper have an integrally moulded body and a separate blade spindle received within a bore formed in the moulded body. The diffuser is mounted on a support connected to the plenum chamber by way of a fastening comprising an integrally formed head and shank which is threaded adjacent its free end, together with integrally formed resilient fingers for retaining the fastening in position on part of the diffuser whilst permitting rotation of the fastening.