This is a set of 3 compatible TH658-1S water filter cartridges for TOTO. I purchased these on Amazon last fall, but I'm selling them because I replaced my faucet. The outer box and instruction manual have some damage, such as folds, but the water filter cartridges are unused and unopened. According to the instructions, the color seen on the edge of the cartridge is due to the resin that secures the hollow fibers. Please understand that these were purchased privately and stored at home. Thank you for looking.