What does Super 120s mean? The federal micron limits behind every wool suit tag

A "Super 120s" label on a suit means the average diameter of the wool fiber is 17.75 microns or finer. That is the federal definition, and it is a law, not a marketing convention. Under the Wool Products Labeling Act, a product tagged "Super 120's" or "120's" is falsely labeled if the average diameter of its wool fiber is not 17.75 microns or finer. The number describes one property of the fiber and nothing else.

Where the number comes from

The Super scale is a numbered grading of wool fineness, and Congress wrote it into the act in 2006. Public Law 109-428, signed December 20, 2006, added the Super number thresholds, and the amendment applies to wool products manufactured on or after January 1, 2007. Since then, a label that claims a Super number has to be backed by a fiber measurement.

The statute, 15 U.S.C. 68b, lists the thresholds from Super 80's up to Super 250's. A few of them, read on the Cornell Legal Information Institute copy of the U.S. Code on October 21, 2026:

• Super 80's: average diameter 19.75 microns or finer
• Super 100's: 18.75 microns or finer
• Super 120's: 17.75 microns or finer
• Super 150's: 16.25 microns or finer
• Super 180's: 14.75 microns or finer
• Super 250's: 11.25 microns or finer

A micron is a millionth of a meter. In the statute's table, every 10-point step in the Super number lowers the limit by half a micron, from 19.75 at Super 80's to 11.25 at Super 250's. A higher number means a thinner fiber, and the law caps how thick the average fiber may be.

What the law does not promise

The statute measures average fiber diameter and nothing more. It says nothing about fiber length, strength, how the yarn was spun, how tightly the cloth is woven or how it is finished. Two fabrics can both honestly carry "Super 120s" and wear very differently. The rule also uses the word "average," so a fabric can contain fibers coarser than the headline number as long as the mean meets it.

There is a second limit worth knowing. The test is applied to "the wool fiber of such wool product," and the same section requires the label to state fiber content by percentage, the manufacturer's name or registered number, and the country where the product was processed or manufactured. A Super number on a tag sits inside that fuller disclosure, so a blend gets a percentage breakdown and the Super claim is judged against the wool part.

What "wool" and "virgin wool" mean in law

The same act defines the word itself. Under 15 U.S.C. 68(b), wool is the fiber from the fleece of the sheep or lamb, or the hair of the Angora or Cashmere goat, "which has never been reclaimed from any woven or felted wool product." The definition may also include the specialty fibers from camel, alpaca, llama and vicuna. Recycled wool is a separate legal term, defined in section 68(c) as fiber made by breaking down wool that was previously woven or felted into a product, whether or not a consumer ever used it.

The words "virgin" and "new" are policed too. Under 16 CFR 300.20, those terms may not describe a wool product that is not composed wholly of fiber "which has never been reclaimed from any spun, woven, knitted, felted, braided, bonded, or otherwise manufactured or used product." So a tag that says "virgin wool" is a legal claim about the fiber's history, and a tag that says "recycled wool" tells you the cloth was made partly or wholly from reclaimed fiber. Neither says anything about whether the garment is good.

Cashmere gets its own measurement in the same statute. A product labeled cashmere is misbranded if it is not the fine, dehaired undercoat of a cashmere goat, if the average fiber diameter exceeds 19 microns, or if it contains more than 3 percent by weight of cashmere fibers over 30 microns. We covered that in our guide to fiber content label rules.

Does a higher Super number mean a better suit

Not automatically, and the law does not claim it does. A finer fiber generally makes a softer, lighter cloth with a smoother drape, which is why the high numbers are used for luxury suiting. But a very fine fiber is also a thinner one, and the statute is silent on durability. If you wear a suit several days a week, a mid-range cloth in a firm weave is a reasonable alternative to chasing the highest number on the tag, and that is our judgment, not a finding of the statute.

The most useful use of the number is as a floor. If a tag says Super 120s, you can hold the seller to 17.75 microns or finer on average. If the tag says only "fine wool" or "luxury wool," nothing in the Super scale applies, because the thresholds attach to the numbered terms.

How to read the tag

Start with the fiber content line and the country line, because the law requires them. Then look for the Super number, and treat it as one measurement among several. Ask for the weight of the cloth in ounces or grams per meter and look at the weave, because those say more about how a suit will hold up. If the tag claims "virgin wool," remember that the claim is limited to the fiber never having been reclaimed.

Where a label does not match the law, the enforcement route is the Federal Trade Commission, which administers the act. We found no published case in this review, so we do not claim a track record of enforcement either way.

Our take

The Super scale is rare among fashion terms because it is backed by a number that the law defines. Use it for what it is: a cap on average fiber thickness. A Super 120s suit is not a guarantee of anything beyond that, and a Super 150s tag is not proof the cloth will last. Check the weight, the weave and the percentage of wool before you pay for a number.