An auxiliary tool to be employed when positioning elements, such as window and door frames is described, in relation to an adjacent flat or plane, such as within wall openings, whereby the auxiliary tool comprises an inflatable air cushion member (6) which through a hose connection means (10) is connected to a pumping device (12) and a bleeding valve (16). The air cushion member is shaped as a flat bag unit. The auxiliary tool furthermore comprises connecting elements (42, 46, 48) for the mutual fixation of an air cushion member (6) comprising one or more adjacent air cushion members which have two or more mutually fixed air cushion members (6) which selectively are inflatable. These are in a side by side relationship provided positioned in a common plane so that in total the flat bag unit sides form opposing sides within the auxiliary tool.