<Ul> <Li> Automatic defrosting </Li> <Li> A power failure warning that alerts the user by flashing a temperature display . It may display the maximum temperature reached during the power failure, and whether frozen food has defrosted or may contain harmful bacteria . </Li> <Li> Chilled water and ice from a dispenser in the door . Water and ice dispensing became available in the 1970s . In some refrigerators, the process of making ice is built - in so the user doesn't have to manually use ice trays . Some refrigerators have water chillers and water filtration systems . </Li> <Li> Cabinet rollers that lets the refrigerator roll out for easier cleaning </Li> <Li> Adjustable shelves and trays </Li> <Li> A status indicator that notifies when it is time to change the water filter </Li> <Li> An in - door ice caddy, which relocates the ice - maker storage to the freezer door and saves approximately 60 litres (2 cu ft) of usable freezer space . It is also removable, and helps to prevent ice - maker clogging . </Li> <Li> A cooling zone in the refrigerator door shelves . Air from the freezer section is diverted to the refrigerator door, to cool milk or juice stored in the door shelf . </Li> <Li> A drop down door built into the refrigerator main door, giving easy access to frequently used items such as milk, thus saving energy by not having to open the main door . </Li> <Li> A Fast Freeze function to rapidly cool foods by running the compressor for a predetermined amount of time and thus temporarily lowering the freezer temperature below normal operating levels . It is recommended to use this feature several hours before adding more than 1 kg of unfrozen food to the freezer . For freezers without this feature, lowering the temperature setting to the coldest will have the same effect . </Li> </Ul> <Li> A power failure warning that alerts the user by flashing a temperature display . It may display the maximum temperature reached during the power failure, and whether frozen food has defrosted or may contain harmful bacteria . </Li> <Li> Chilled water and ice from a dispenser in the door . Water and ice dispensing became available in the 1970s . In some refrigerators, the process of making ice is built - in so the user doesn't have to manually use ice trays . Some refrigerators have water chillers and water filtration systems . </Li> <Li> Cabinet rollers that lets the refrigerator roll out for easier cleaning </Li>

When was the side by side refrigerator invented