Expiration Date: February 2027 Two Tornado Sticks. These are replacement cartridges specifically for the Science shower head 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 shower heads from other manufacturers.