I had a chance to pick up a Kalashnikov Concern AK12 Grip Assembly this week, and I really am impressed with the build quality and features. The grip itself appears to use a similar mounting interface with previous generation AK grips, except this unit has a shorter screw allowing for storage space inside the grip. The storage space is filled with a rather well engineered pop-out oil container, that is removable as the user pushes on two buttons. I am unsure what the factory proof marks indicate, and will try to update this post when I do.