Expiration date: January 2027 Two Tornado Stick cartridges. These are replacement cartridges specifically for the Science showerhead Mirable. Compatible with Mirable Plus, Mirable, Mirable Zero, and Mirable ZERO. [New, Unused] Replacement is recommended approximately every 1 to 3 months. (Replacement frequency varies depending on usage, water quality, and conditions.) Dechlorination performance varies depending on water quality, temperature, and other conditions. * Replacement frequency will be shorter if the water temperature is high (over 40 degrees Celsius) or if the chlorine concentration is high. Cannot be used with showerheads from other manufacturers.