Water purifier. Coloured scanning electron micrograph (SEM) of the polyacrylamide ion- exchange resin from a water purification filter. The resin removes ions such as metals, chlorides and sulphates from water passed through it. The rest of the purification unit (not seen) consists of coconut shell charcoal to remove odours and gases, and a ceramic housing to filter out solid material. Magnification: x4025 at 6x7cm size.