Horse rug listings throw around denier, GSM, and fill weight as if they're interchangeable, and that confusion costs buyers money. A 300 GSM polar fleece rug and a 300g poly-filled turnout rug are not equally warm | one measures fabric weight, the other measures insulation. Mixing these up means a brand can end up marketing a rug as "300 GSM, extra warm" when the actual insulating fill is zero.
There's a second, quieter problem: some suppliers keep the denier rating the same across product generations while quietly reducing the GSM | so a "1200 denier" rug today might use a noticeably thinner, lighter fabric than the same rating five years ago, even though the label looks identical. Buyers comparing rugs by denier alone, without checking GSM, can end up with a weaker product than they expect.