I ordered this shirt and the "Gildan 5.3 oz Heavy Cotton T-Shirt" to compare. This "Men's Gildan Ultra Cotton T-Shirt" is definitely heavier cotton than the "5.3oz Gildan Heavy Cotton T-Shirt". Therefore, a "heavy cotton" shirt is thinner. I'm assuming it's "Gildan Men's Ultra Cotton T-Shirt". is 6.0 ounces. or more. This is the best quality. The 5.3 oz Gildan Heavyweight Cotton T-Shirt is back.