0. 25mm i. d. DXi internal standard tee (PFA, green marker) Attaches to port #3 (DXi Version). Specially designed mixing tee is perfect for online addition of internal standard or online dilution. Achieves excellent mixing with minimal dead volume. 0. 5 mm i. d. capillary is recommended for applications with fl ow rates> 0. 3 mL/min.