120u (microns)
120u refers to a 120-micron (µm) sieve, the mesh size used to sort trichomes when separating hash. The smaller the micron, the more selective the fraction.
A mature trichome head measures roughly between 70 and 120 microns. Filtration bags typically range from 220u (coarse, lets plant debris through) down to 25u (the finest): the 70-120u fraction concentrates whole heads, and that is what extractors are after. Hash labelled 120u was sorted at that mesh; a 73u-90u is a narrower fraction still, a candidate for the full melt grade.
Stating a micron is a sign of seriousness: the producer is willing to say how the hash was sorted, and the figure can be checked against the observed texture. But the micron says nothing about potency: only the batch certificate establishes the dominant cannabinoid and compliance with the French 0.30% Δ⁹-THC threshold.
In our lab, the 120u (ice-water separation) measures 15.9% CBD, and the 90µ CBG Hash, sieved one mesh finer, 19.3% CBG.