BlueLab PH 7.0 Calibration Solution， 500 milliliters</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>PH instruments are calibrated to pH 7.0 first (buffer) then to pH 4.0 (slope)</li><li>Store in a cool place out of direct sun and heat</li><li>They should be stored with the lids securely tightened</li></ul></div></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br><img src='http://ecx.images-amazon.com/images/I/31%2BtFnlFiJL.jpg' noproxy></br>