Buy Elgi Ultra Dura+ Wet Grinder, Fortune White ...
The description says litres but the batter produced is close to litres in this grinder and the size of the container is close to 5 litres. A single idli may require about 4075 ml of batter and a dosa about 100150 ml of batter. Since batter should not be stored longer than a week, this size is adequate.