Buying a headset for MTB

Hello!

I am trying to find out what kind of headset would fit my mountain bike. I think my frame has an Integrated Steerer and an External Cup

For the External Cup I have measured it at 40.2mm (plus, minus since it may be inaccurate) and the integrated steerer is at 32.5mm and my fork is measured at 28.5mm.

Can anyone suggest me what kind of headset should I get for my bike?