This is a part that came with the LIXIL INAX SF-WL420SYX single-lever kitchen faucet. It's a necessary part for attaching aftermarket water purifiers, etc., to single-lever faucets with internal (female) threads on the aerator. It is also compatible with TOTO single-lever kitchen faucets with internal (female) threads. The item in the photos has been opened for photography, but you will receive a new, unopened item.