This mean, we will get the smaller spot and the more concentrated energy at this plane.
However, sometimes we don't need this "powerful small point" and we would prefer a thicker line for speeding up the works or creating different patterns. This can be very easy achievable by unfocussing a little the laser so we can use these extra gauges for that purpose (47, 50 and 55mm).
You can check the Addons page or download the extra gauges directly here.