Abstract: A sealing member for the straight moving leading edge of a curtain system, such as is used for example in greenhouses to control the heating and/or lighting conditions, consists of an extruded L-section body with at least one flexible sealing element protruding from a first leg and a second flexible element protruding from the second leg when more complete sealing is required. Preferably the sealing element of the second leg protrudes perpendicularly, while that of the first leg protrudes at an angle away from the second leg. The two sealing elements extend the full length of the body and the curtain edge first engages the first element and bends it toward the first leg and then engages the second element, if present, and also bends it towards the first leg so as to form a sealing space between them. Both elements are held positively in sealing contact with the curtain leading edge by the resilience of the material of the elements.