Advertised as being upto 60mm but realistically it will fit 34-40mm as a maximum, 60mm between the fully open tips. Seems to cut near anything that fits the jaws. Its quite impressive what it will cut! Some harder stuff takes 3 or 4 presses. It will do 60mm ivy if you do a few cuts 2 inch apart. Its not going to damage the bark like a chainsaw could if you trim ivy with this.
A photo will show it better.
I notice theres some chipping/rolling/damage on the jaws after todays use. I only used it on branches, some perhaps too hard and thick. I let my buddy use it for some hedge and doubt he would have hit metal or would have told me either way.
Anyway they are thick and easily resharpened which will give a bigger opening. I wont use the cheap included stone..