Thank you for viewing. This is a water purifier cartridge. I had it in stock, but I'm selling it because I changed the faucet. It is equivalent to and can be replaced with TOTO's TH634-2, TH634RR, KNTH634-2, etc. Also, since TOTO is an OEM (Original Equipment Manufacturer) of Cleansui, it is also compatible with Cleansui's UZC2000, UGC2000-GR, BUC12001, HUC17021, etc. 【Caution】 The manufacturer officially announced that many counterfeit products are circulating even if the Cleansui or TOTO logo is printed on them, so I personally think that the sellers who are selling them cheaply on Mercari are quite suspicious. I think it's strange that it's half the price of the genuine product on Amazon... → I think the compatible product is more honest than the fake one. TOTO https://jp.toto.com/importantnews/info_important_others_20231219/ Cleansui https://cleansui.com/brand-protection Although it is a compatible product, I have been using the same one for about 3 years and have had no problems at all. Thank you.