Greenhouse Automatic Roof Window Opener
The opener has a metal cylinder containing a mineral which explandswhen heated. This pushes a piston that opens the vent. As thetemperature cools, the mineral shrinks and a spring closes the vent andresets the piston. The opening and closing of the vent is gradual,allowing just the right amount of air flow for cooling.
This Automatic Roof Window Opener has a 7-year warranty againstmanufacturer's defects and is very lightweight at 3 lbs. The opener canbe installed on all Rion greenhouse roof windows
Source: snappdragon.comAdded: 28 March 2008