Includes 4oz each of 4.00 and 7.00 buffers. We package these solutions from bulk quantities to get you the best pricing. For testing, pour buffers into a small glass. You do not want to stick the probe of the pH meter into the buffer jars directly because you will eventually sacrifice the accuracy of your buffers. Expires after 6 months if unopened. Expires after 3 months if opened. Click here for a PDF of the MoreManual on proper pH Meter care.