Concrete Masonry units are typically manufactured with nominal modules (including the thickness of mortar joints) of 4 inches. These English unit conventions can be converted directly into metric equivalents. For example, an 8 x 8 x 16 inch modular concrete masonry unit has metric dimensions of 203 x 203 x 406 mm. NCMA recommends that buildings that are designed using metric measurements, use these "soft" metric dimensions. "Hard" metric units (200 x 200 x 400 mm) can be manufactured, but at possibly very large expense.