How to use mask extracted from a product into another one

Exactly after i did classification i want to extract a mask representing only one of the classes obtained in classification output.
With such mask i want to clip the original rasters with land/sea mask applied on it to obtain only those pixel belonging to the class i’m interested and then eventually perform a more detailed classification only in such remaining ROI.
I hope i’ve explained what i mean.

I succeded to get the class-mask but is there a way to use it in land/sea mask on a different product than the classifier output?

Thanks in advance.

A quite similar question was recently asked here: How do I extract value from one raster to another raster

Does my answer there bring you forward?

@ABraun
thanks for helping,
i’ve read that post and that’s similar to my purpose, but the main difference is that i want to clip (land/sea mask) all the rasters in one product using the mask (only one class) i obtained from the classification.
Further use the clipped images to perform a more detailed classification only on those clipped rasters.
From the post you suggest seems that i have to do a collocation with both products (rasters’ file and classification output) then i extract the mask and thus clip them.
Is it right?
And most of all do you think it makes sense or i would obtain the same results if i just use more detailed classes in the main classifier directly?

To me it makes sense to exlcude areas of a pre-classification to have only areas of interest remaining for a second classification.

So you make a mask with the mask manager defining the areas of your class of interest.
In a second step you apply this mask to the product to exclude all pixels outside the mask.
Then you can apply a second classification on the remaining product.

Ok got it, the first step is the collocation and then process all the rest.
Thanks.