Although it is new and unused, the box is slightly crushed. This is a set of 2. These are replacement cartridges specifically for the Science showerhead Mirable. They can be used with Mirable Plus, Mirable, Mirable Zero, and Mirable ZERO. 【New, Unused】 The replacement目安 is approximately 1 to 3 months. (The replacement目安 varies depending on frequency of use, water quality, and usage conditions.) The chlorine removal performance varies depending on water quality, temperature, and other conditions. *If the water temperature is high (over 40 degrees Celsius) or the chlorine concentration is high, the replacement frequency will be shorter.