Disinfectant for humidifiers

I mistakenly purchased the wrong type of filter for my humidifier and am now selling it.
I've listed it as near unused, but one filter's seal was opened just to confirm it wouldn't fit the tank opening, so it's practically new and unused. However, please refrain from purchasing if you are concerned about this.
This is a set of two, and the other one is unopened.

Please refer to the photos for details.
Purchase price: 1000 yen

*Immediate purchase is welcome.
*Price is non-negotiable.