Royal Victorian Automatic Opener for Louvre Window

Automatic Opener for Louvre Window for Royal or Junior Victorian Greenhouses: the black tube is filled with special parafine oil - which expands when the temperature reached around 72º and the piston will push the window open up to about 14". When temperature falls a heavy spring pulls the window closed. No electricity needed! Specifications: Fully automatic - no electricity needed! Opens to approx 14" Black color