Oakton's Flushable, Double Junction, Epoxy-body, Refillable pH ElectrodesFeatures a flushable Teflon junction - use with substances that ordinarily clog standard electrodes.Ideal for testing dirty water slurries, oils, paints, pastes, low ionic strength solutions, and solutions with heavy metals or organics. Flushable annular junction lets you refresh junction by pressing electrode cap - cleans clogs instantly.