I inherited a 6x4 Halls greenhouse. I wanted to fit a roof vent but three suppliers informed me this would not be possible due to the age of the greenhouse. Then I spoke to Ian at Elloughton's. He contacted Halls, called me back to tell me it was feasible and the window vent arrived four days later! Worth knowing: although I dealt with Ian, the window vent came direct from Halls. The instructions were less than helpful However, there's a friendly Dutchman on YouTube: 'EasyStart Greenhouse Page F Assembly' where you'll get useful information to set you on the right track. Took me about an hour. Thank you Elloughtons - excellent service!