Wrapping a unmanaged C++ class

Hi!

I have a structure defined in my old unmanaged class, which is a output parameter of one of my methods. I want to create a managed C++ class which "wrappes" my old one.... the question is:

Which Marshall Type Conversion must I use in order to pass the information of this structure to my managed class and viceversa?

CODE
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void Extract( Feature* *MyFeature);

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Feature is the structure which is really the output of my method...

Thanks in advance!!!