Abstract: An insulation system for use in a greenhouse, comprising at least one insulation panel adapted to be mounted in the ceiling of a greenhouse, and means to move the at least one panel from a closed position to an open position, whereby when the panel or panels are closed, air below the panels remains in the area of the greenhouse below the panels, and when the panel or panels are open, air below the panels can move to a space in the greenhouse above the panels.

Abstract: In a snap connection system in which a shaft is inserted into a tube to a predetermined position, where co-operating surfaces on tube and shaft engage as in a laterally acting wedge. Two axially spaced spring loaded balls on one side of the tube urge the shaft into wedging engagement with the tube when in the pre-determined position. During insertion, a further spring loaded ball on the opposite side of the tube adjacent the wedge apex urges the shaft out of wedging engagement with the tube. A detent in the shaft accommodates this further ball at the predetermined position, locating the shaft axially and permitting wedging. The balls are biased by a spring sleeve and a tang thereon locates the sleeve on the tube. The tang may extend to the tube interior to coact with a detent in the shaft so that unclipping is necessary for disassembly. Alternatively, a spring loaded pin extending through sleeve and tube wall may accomplish the same end.