Opens and closes your greenhouse window as temperatures fluctuate. Can be preset to operate at temperature of your choice. Easy fit. Maximum window opening approximately 45cm/18” Maximum opening at 30°C/86°F depending on ajustment and load. 1 Year Warranty Price: $ 69.95                                                                                                                                              AGL Vent Opener AGL  vent opener offers fully automatic greenhouse ventilation and it works by means of solar energy.  AGL vent opener will remember to open at this temperature whether you are at home or not .  AGL opens the window completely (45°CM) which means Maximum ventilation per window and an ideal climate for greenhouse plants. Price: $ 45.00                                                                                                                                              Bayliss MK 7 Simple – Strong, Easy To Fit Easy to fit – Screws included for ftting to most Aluminum or Timber Greenhouses. Easy to set – One simple ajustment. Solar Powered – Non electric Strong build – Balanced double arm lifting action eliminates vent twisting. Anodised Aluminum Construction  - All parts corrosion resistant.                                                                                                     Spring controlled – Avoids wind damage when                                                                                                      opening and closing.  Quality assurance – All                                                                                                       parts guaranteed.  Suitable for opening hinged                                                                                                      vents up to about 2ft 6in square (75cm,square) of                                                                                                       normal construction.                                                                                                      Price: $ 85.00                                                                                                                                      Bayliss MK 7 with Hydraulicheck                           The addition of a small hydraulic damper which we have called the "Hydraulicheck" to the Mk 7 offers the best answer yet provided to the problem of wind damage on greenhouse and conservatory vents. It only allows the vent to be opened slowly but it can be shut quickly.  Whilst the Mk 7 Triple Spring model offers an adequate degree of protection in most positions, the Hydraulicheck fitting is advisable in areas where severs conditions are encountered. Thy Hydraulicheck is a single acting hydraulic damper fitted between the arms of the Mk 7 Autovent. The resulting unit appears very similar to the Triple Spring model and is identical in size and performance. Price: $ 195.00                                                                                                                                                       Univent Univent offers automatic ventilation of all cold frames, greenhouses, concervatories, stables etc. Univent is very suitable for garden frames and doors. Is easily taken apart by single clutch so that the garden frame or the door can be fully opened. Has extra strong lock and back- stop springs,can be applied on top- hanged windows vertical walls, gives extra support in windy weather. Has an opening height of 48cm which means maximum ventilation, liftsup to 7 keg, that means windows weighing up to 14 kg .  It is made of rust proof materials lasting for many yrs. Is easy to fit. Price: $ 59.95