Crankcase ventilation question???

Is this box (arrowed) use for crankcase ventilation??? And does have any specified size? Oh yes and why is this better than the regular?

Looks like an oil catch tank to me ? Similar to the sort used for motor sport .

Is this good or bad?

I have a catch tank on my mk2 escort track car. What its good for is taking the crankcase fumes and not letting them go through the engine ie into the inlet manifold as this causes pinking and ruins performance.