The Gaggenau SK535 refrigerator is fitted with a water filter for the integral ice and water dispenser, part reference WF 535-001.
The filter is actually manufactured for Gaggenau by Amana, who also use the cartridge in some of their own branded refrigerators (Amana part ref: Puriclean II) aka UKF8001.
The Puriclean II cartridge is certified to remove chlorine, lead, atrazine, lindane, benzene, and mercury. This carbon based cartridge will significantly improve the taste of mains water.
The cartridge is easy to install with a simple 'push-and-twist' mechanism.
This cartridge is designed to be replaced every 6 months (or 2,000 litres of water) or when the 'replace cartridge' light comes on (if fitted). If the fridge is switched off and remains unused for any period of time greater than two weeks (e.g. moving house), the manufacturer recommends changing the cartridge.
Got exactly what I ordered. No problems whatsoever. Easy to use as well.