How to choose the size of Reference Electrode? The diameter of   ERA131B [ Silver Silver Chloride Ag/AgCl Reference Electrode Φ4*50mm Glass Rod ]   glass tube is 4mm, which is not the best choice for CHR221B2. The diameter of   ERA131A [ Silver Silver Chloride Ag/AgCl Reference Electrode Φ6*70mm Glass Rod ] is 6mm, which is more suitable for CHR221B2.     L et me   briefly introduce this electrochemical cell for you.I attached two images, so you can see it clearly: Figure 1   is the default opening diagram of   CHR221B2 [ H-Type Sealed Electrochemical Cell 30ml 45ml ] .   The left side is the working electrode chamber opening diagram, and the right side is the counter electrode chamber opening diagram. As shown in the parameter diagram on our product details page, we place the working electrode and the reference electrode in a chamber, and are equipped with gas inlet and outlet holes [for inert gas protection and oxygen-free operation]. We placed a counter electrode in another chamber