HI76483A/P is a replacement dissolved oxygen screw cap membrane manufactured for Hanna's HI76483 DO probe. The cap is made of durable plastic material with a polytetrafluoroethylene (PTFE) oxygen-permeable membrane. Each cap is easily filled with electrolyte and installed on the probe. PTFE membrane separates the probe cathode and anode from the sample being measured. Oxygen passes through the membrane and interacts with the polarographic system, producing an electric current proportional to the oxygen concentration.