The THF-F400 clean filter, made by TOYOTOMI, is a replacement cartridge specifically for the THK series hybrid humidifier. - Model: THF-F400 - Brand: TOYOTOMI - Filter Type: Clean Filter - Compatible Models: THK-F400, THK-WD400 ◎ This is an unused item, but it was purchased some time ago and stored at home, so the outer box is damaged. ◎ The filter is sealed in film, so it is believed to be in good condition.