The 9210 provides easy maintenance of well-constructed triple point of water cells. This is simply done by inserting the cell into the apparatus and entering ‘freeze’ mode from the front panel buttons. An audible tone will sound to indicate when the cell needs to be taken out and shaken. Re-inserting to cell and selecting ‘maintain’ will give you 0.01°C for the rest of the day with uncertainty of only ±0.0005°C.