You need a Caliper
Exterior Diameter
This is the outside diameter of the top of the portafilter without the ears or tabs
Diameter with ears
Exterior of the ears or tabs, the widest part that includes the ears or tabs
Diameter with ears is it has 3 ears or tabs
Exterior of the ears or tabs, from the outside of one ear to the exterior of the main body
Distance from basket lip to bottom of ears or tabs
Place portafilter on very flat surface, like glass or mirror - flat against bottom of the ears to the flat surface
Ears or tab size
how big are the ears - also if possible a top view photo is necessary
Inner Diameter
and the inside diameter of the basket.