Bluelab PROBPH pH Probe, Replacement Probe with BNC Fitting, Easy CalibrationReplacement pH probe for Bluelab meters used for measuring in solution Fully waterproof probe is easy to clean and calibrate Gel filled with double junction reference to improve lifespan Made with lab quality glass; Probe holder included; BNC fitting with 6. 6ft standard cable Supplied by Bluelab, the industry leader in hydroponic testing equipment; 6 Month Limited Warranty with proof of purchase