Measuring air flow velocities and correctly calculating the volume flow at ventilation outlets can present a challenge. Use the Testovent 417 funnel set (in conjunction with the appropriate measuring equipment) to measure the volume flow at ventilation grilles and plate outlets conveniently and accurately. Using the funnels will save you time, since there is no need to use the time-consuming loop method for calculating the mean. The Testovent 417 funnel set consists of a funnel for ventilation grilles and a funnel for plate outlets. You can conveniently transport both funnels in the practical case.