Testo-0563-4171-417-Vane-Anemometer-Set-1-plus-Funnel-set-0563-4170-Testo-0563-4171-P-The-measurement-of-flow-velocity-&-the-correct-calculation-of-volumetric-flow-from-ventilation-outlets-can-be-a-challenge-The-turbulence-created-&-differing-flow-directions-make-correct-measurement-more-difficult-P-P-The-Testo-417-vane-anemometer-supplied-in-a-set-with-two-measurement-funnels-&-other-accessories-provides-you-with-perfect-support-for-flow-measurement-from-ventilation-grilles-an