A keyboard case is the housing in which all the parts go inside. Its primary function is to protect the internal parts. It also provides the bulk of the weight of the keyboard. It affects the acoustics and the aesthetics. Cases are usually built to accommodate a single PCB; the PCBs are usually sold with the keyboard. A notable outlier is the 60% tray mount keyboards. Most 60% tray mount PCBs will have holes that line up with the famous Pok3r PCB; most 60% PCBs-dz60, dz60RGB, gh60, gk61, gk64, bm60, and even the boardwalk-are compatible with most 60% cases.