The filters come in different sizes:
11mm and 12 mm filters are used in diamond microdermabrasion wand;
16mm and 18mm filters are used in vacuum output.
To determine suitable size of filter you need, measure the opening of the treatment wand on the end where the tip is attached. Wands from different manufacturers may have slightly different diameter of the opening.
To determine suitable size of filter you need for the vacuum output, measure the diameter of the vacuum knob.