It allows you to chose the correct hose diameter which adjusts the values for the alarm. When it sounds, it's telling you :
you have the suction hose blocked or kinked.
filter bag full.
filter element clogged.
Which means there will be more than the allowable particulate put back into the air. Which is what gives the H&S guys a big boner.
I've never clogged a filter on a CT in two decades and can pretty easily tell when I have a kinked hose, so the CTM is really only offering a bag full indicator. At an increase in cost and complexity. There is no magic suction or "better" or finer filtration with a CTM . It's simply a product offering that allows uses to comply with government regulations in the markets its offered.