An awesome tamper if you are finding that your coffee is really fresh, the infusion base has circular raised indentations on the surface. These indentations increase the surface area of the coffee, and cause a 'pre-brewing' effect during coffee extraction as the water passes through the coffee puck. The effect is a change to the flavour profile and acidity of the coffee, as compared with the flat base. In general terms, the flavour created by this base is sweeter as compared with the flat base, however the exact impact is dependent on the coffee beans/roast used. It also has a compression spring to allow for more consistent extraction especially when you are sharing the espresso machine with a few Baristas.