Restoring posterior teeth is about 80% of our daily practice, and most cavities are CL II type, and restoring a healthy and functional proximal anatomy, requires understanding and analyzing natural shape and morphology in each space in posterior segments, referring to creating correct sizes, profiles and, most importantly, height. As that the proximal ridges are, in fact, the guide plane for occlusal movements. So, understanding the matrix and the tools that is being used as the key for a successful posterior restoration. This lecture is a summery for natural proximal morphology and discussing CL II types, highlighting a modern concept for the matrix selection in deeply seated lesions and the shallow progressed types