What is the 1-4 function, and how does it work?

The 1-4 button should be activated when you are making less than 4 cups of coffee. By pressing this function it will slow down the brewing process so you are receiving a strong cup of coffee. If you make less than 4 cups and do not use this function the water will pass through to quickly thus resulting in a weak tasting coffee. If you make a full carafe of coffee and choose this function the unit will brew very slowly and still result in a full carafe of coffee.