Easy To Fit And Very Unobtrusive The Unit Can Be Set To Start Opening The Louvre Vent Between 15oc And 18oc Helping To Automatically Control The Temperature In Your Greenhouse. it Is Supplied With A Backplate Enabling Users To Fit It Using Existing Holes On The Majority Of Louvre Vent Systems. bayliss Automatic Louvre Window Opener - Made In The Uk2 Year Manufacturers Guaranteecan Be Used On Our Louvre Window Kiteasy To Fit And Unobtrusivecan Be Set To Start Opening Between 15oc And 18ocmaximum Opening Around 30ocsupplied With Backplate For Fitting To Existing Systemslouvre Window Opener Measures 210mm X 52mm X37mmplease Note: This Is Not Compatible With The Harrod Superior Greenhouses.