Fine-grain power gating encapsulates the switching transistor as a part of the standard cell logic. Switching transistors are designed by either the library IP vendor or standard cell designer. The K-box is about the size of a standard cell (mobile) phone. In standard cell culture, diffusion is often the sole means of nutrient and metabolite transport. The sum of these potentials is the standard cell potential or voltage. A standard cell library is sometimes called a "macrocell library". The standard cell library comprises many different logic gates, for example a NAND gate. The market focus is standard cell library design and optimization for 14-28 nanometer CMOS processes. "Standard cell" falls into a more general class of design automation flows called cell-based design.