REFILL CARTRIDGES: This product includes refill cartridges for the Hello Klean Purifying Shower Head 1.0. It includes one Headpiece Cartridge, one Handle Cartridge and one small wrench for easy installation. These refills are not compatible with the newer Hello Klean Shower Head 2.0. HOW TO INSTALL THE HEADPIECE CARTRIDGE: Place the small wrench which has been provided onto the tip of the shower head. The handle should be facing outwards. Press and steadily turn the headpiece counter clockwise. Now all that is left to do is to replace the used circular cartridge. HOW TO INSTALL THE HANDLE CARTRIDGE: Simply twist the bottom handle counter clockwise and replace the carbon cartridge. HOW OFTEN SHOULD YOU REPLACE: Each refill cartridge will purify 13,000 litres of water. For a household of 1, this would typically last around 4 months. For a household of 2, this would typically last around 3 months. SPECIALLY SELECTED INGREDIENTS: The Hello Klean Shower Head Refill Cartridges contain three key ingredients which help to purify water. KDF 55 helps to reduce water soluble metals such as lead, iron, copper, mercury and nickel. Amino Acids help to boost filtration whilst Activated Carbon Fibre reduces trihalomethane (THMs) and odour., Manufacturer: Hello Klean