Talk about chloroplast membrane.

Two membranes bounded, thick membranes with wide intermembrane space outer chloroplast membrane (OCM) like OMM contains porins which makes it permeable to a variety of molecules, other proteins are also present in the OCM. ICM is far less permeable, and has different properties since they differ in composition, so the ICM regulates transport of molecules from stroma to cytosol and vice versa