Unique Glass Membrane - The PHE-15 HF glass membrane, which has a faster response rate, better repeatability in strong acid samples, and resistant to hydrofluoric corrosion. Silver Ion Trap Reference System - The PHE-15 pH electrode uses a Silver Ion Trap reference system. On top of the Long-Life reference system, a silver ion trap is added to prevent the junction being blocked by silver sulfide. The electrode uses a BNC connector, compatible with all labForce® pH meters.