Catastrophic product...inacurate compare to two or three other salanity checker...as neptune, milwaukkee and on and on Offset by 2 ppt.... Ot seems that hanna is using another calibration solution...... If you calibrate it with neptune solution...it will resd as neptune is.... If you calibrate it with accurasea it will read as othernthat have been calibrated with it... But when calibrated with hanna liquids...... Ot will then be offset...... Hanna keep saying that their products is THE one that must be followed.... Your choice to decide..... @ Hugo we appreciate your review, we helped you last month and determined the unit was defective and also agreed to send you a new one once we got the bad one back. Im not sure why you would rather review a defective unit rather than getting it replaced under warranty. Your choice to decide I guess