This is a use-then-dispose-of in-line-softener

Your meter will be perfectly fine and the small extra bottle is included for this purpose

as the filters are listed below

Re-calibration can be done separately or each line

Softening Filter In-Line FilterPacks This is a use-then-dispose-of in-line-softenerInline Water Softening Filter Introducing Air, Water & Ices in line water softening filter! If you dont already have a water softener in your house, and youre looking to invest in a water softener, then this is the filter for you. Consider adding this softening filter as a pre filter in front of your RO unit. Not quite the right filter for your system? Please check out all our filters here. How the Inline Water Softening Filter Works: The filter works