A knee airbag assembly comprises: a knee airbag cushion having a primary gas distribution inflation chamber for housing an inflator or is formed with a gas inlet for receiving inflation gases and a plurality of additional chambers (114, 115, 116), each additional chamber being attached to an adjacent chamber and having an opening between adjacent chambers for receiving inflation gases; an inflator for providing inflation gases to or into the primary chamber the inflator being connected to a gas inlet of the primary gas distribution chamber or positioned therein said chamber and wherein one or more of the additional chambers (114, 115, 116) has the opening formed with a one-way gas flow check valve for receiving inflation gases on inflation, but preventing back flow or reverse flow back into an adjacent additional chamber or primary chamber, wherein the primary gas distribution chamber on inflation projects extending from under a dash of a vehicle toward a front seat, characterized in that the knee airbag cushion has three additional chambers, two outer restraint chambers (114, 116) providing leg protection and occupant restraint and one inner additional small chamber forming part of an adjacent to the primary gas distribution chamber, the inner additional small chamber having a one-way check valve positioned at the opening between the inner primary chamber and the adjacent outer chambers, the check valve being a fabric layer over the opening that bulges out on inflation filling the two outer restraint chambers (114, 116) and on full inflation are prevented from back flowing gases into the inner additional small chamber and the primary chamber as the fabric layer covers the opening the inner additional small chamber has a reduced volume relative to the two outer chambers (114, 116) and the primary gas distribution chamber, and is located slightly forward and on top of the primary gas distribution chamber and is configured to pass inflation gases to the two outer restraint chambers (114, 116) which are located vertically above the inner additional small chamber and upon reaching an inflation pressure exceeding that from the primary distribution chamber the fabric layer or layers closes back over the opening sealing it to effectively maintain the protection restraint chambers (114, 116) in a fully inflated condition regardless of the condition of the lower chambers (111, 115). a knee airbag cushion having a primary gas distribution inflation chamber for housing an inflator or is formed with a gas inlet for receiving inflation gases and a plurality of additional chambers (114, 115, 116), each additional chamber being attached to an adjacent chamber and having an opening between adjacent chambers for receiving inflation gases; an inflator for providing inflation gases to or into the primary chamber the inflator being connected to a gas inlet of the primary gas distribution chamber or positioned therein said chamber and wherein one or more of the additional chambers (114, 115, 116) has the opening formed with a one-way gas flow check valve for receiving inflation gases on inflation, but preventing back flow or reverse flow back into an adjacent additional chamber or primary chamber, wherein the primary gas distribution chamber on inflation projects extending from under a dash of a vehicle toward a front seat, characterized in that the knee airbag cushion has three additional chambers, two outer restraint chambers (114, 116) providing leg protection and occupant restraint and one inner additional small chamber forming part of an adjacent to the primary gas distribution chamber, the inner additional small chamber having a one-way check valve positioned at the opening between the inner primary chamber and the adjacent outer chambers, the check valve being a fabric layer over the opening that bulges out on inflation filling the two outer restraint chambers (114, 116) and on full inflation are prevented from back flowing gases into the inner additional small chamber and the primary chamber as the fabric layer covers the opening the inner additional small chamber has a reduced volume relative to the two outer chambers (114, 116) and the primary gas distribution chamber, and is located slightly forward and on top of the primary gas distribution chamber and is configured to pass inflation gases to the two outer restraint chambers (114, 116) which are located vertically above the inner additional small chamber and upon reaching an inflation pressure exceeding that from the primary distribution chamber the fabric layer or layers closes back over the opening sealing it to effectively maintain the protection restraint chambers (114, 116) in a fully inflated condition regardless of the condition of the lower chambers (111, 115).