A high velocity impinger (Ref. AGI-4) which passes 12.3 to 12.6L/min. (corrected to engineering standard gas conditions) when the pressure drop across the orifice is 41cm Hg or greater. Stopper fits 24/25 125ml bottle and features a 11mm OD center tube, 8mm OD side arm with bulge, 0.05in capillary tip that is positioned 4mm above the bottom of the bottle.