These valley plates are sturdy finned aluminum that fit good. These plates come pre-drilled ready to install, you will need to supply the gaskets. They have been designed for traditional dress up and decorative purposes, they are not intended to fit original backflow breather systems but could be modified to work. Each plate is constructed with a center core thick enough, so that it maybe drilled to accept your pipe work and the underneath side has a formed lip suitable for attaching a sludge tray should you so choose.