Mommes (mm), traditionally used to measure silk fabrics, the weight in pounds of a piece of fabric if it were sized 45 inches by 100 yards. One momme = 4.340 grams per square meter; 8 mommes is approximately 1 ounce per square yard or 35 grams per square meter.
The momme is based on the standard width of silk of 45 inches wide (though silk is regularly produced in 55-inch widths, and, uncommonly, in even larger widths).
The higher the weight in mommes, the more durable the weave, and the more suitable it is for heavy-duty use. And, the heavier the silk, the more opaque it becomes. This can vary even between the same kind of silk. For example, lightweight charmeuse is translucent when used in clothing, but 30-momme charmeuse is opaque.