GSM stands for grams per square meter and it indicates how plush a towel is. Thin, lightweight towels tend to be under 400 GSM. Average-weight towels, like beach towels, are usually 400 - 600 GSM. Any towel above 600 GSM is considered (by the experts, of course) to be a luxury towel. OURA’s Alta towel hits the sweet spot of 650 GSM: it is ultra-absorbent and eternally soft, without being inconveniently thick and dense. In other words, it’s top-quality.