O2 Union 6 to 4 mm I, one-touch€ 7,00 One-Touch (Push-to-Connect), 4 x 6 mm, I union. Available on back-order O2 Union 6 to 4 mm I, one-touch quantity Add to basket Categories: Adapters & parts, Oxygen Description Description O2 Union 4 x 6 mm I, one-touch. To connect the smaller 4 mm air tube to the wider 6 mm tube. Related products SaleOxygen/OximeterContec Pulse Oximeter – OLED € 39,00 € 25,00 Add to basket Oxygen/Oxygen cylindersLight steel cylinder – 1, 2 or 3 liter € 145,00 – € 209,00 Select options Oxygen/Adapters & partsO2 mounting bracket for MH AL-248/415/682 cylinders € 59,50 Add to basket