HI 981410 EC tester has been specifically designed to address the needs of operators in hydroponics, greenhouses and nurseries. Calibration is easy and completely automatic. Simply press and hold the on/ off button for a few seconds and the meter will request the appropriate calibration solution. Place the probe in the solution and wait until it is calibrated. No extra buttons to push or dials to turn! HI 1220 probe measures 24 cm ( 9.4 " ) and can be used to mix the fertilizer solution. The meter switches off after five minutes of inactivity to save battery life. The outer casing also incorporates a molded eye so that the meter can be hung right where it is needed. Order Information: HI 981410 is supplied with HI 1220 EC/ TDS probe ( L: 240 mm) with DIN connector and protective sheath, batteries and 5.00 mS/ cm solution sachet.