Feature cells, are special cells that you create using global variables and equations, grouped in a parameter set, to define their dimensions, or parameters. A single feature cell can have many parameter sets, covering its various allowable sizes, which lets you choose the correct set of dimensions at placement time. Feature cells are placed with the Place Feature Cell tool and may be edited with the Edit Feature Cell tool. During editing, you can select another parameter set to apply, or you can choose another feature cell.