Air purifier filter providing clean water with Ag+ technology. - Brand: SHARP - Model: IF-ZK01K4 - Contents: 2 pieces (2 out of 4 have been used) - Function: Antibacterial effect with Ag+ technology - Condition: Unused, new Thank you for viewing. This is a cartridge for a SHARP humidifying air purifier. I bought a set of 4, but after using 2, I got rid of the air purifier, so I'm offering these to someone who needs them. 2 pieces are unopened and new.