Abstract: An adjustable, spring-loaded support mast which is affixed to standard flow hoods in order to maintain the hoods in position over ventilation registers and diffusers while air flow measurements and adjustments are made. The mast is adjustable in length to accommodate different ceiling heights and is spring loaded to facilitate the positioning and removal of the flow hood over the diffuser as well as to hold it firmly in place. This allows air flow adjustments to be made much more quickly and efficiently, saving time, expense and manpower.