Square tube sizes and thickness 358: 0. 73 2. 60 True 80 XH 100 120 140 True 160 XXH 1/8 0. The thickness of square tubes is mentioned as gauges. You can view our various steel Square Tube sizes and specs for sale below. We can cut to any size to suit your application's needs. 5 3. Ms Square tube sizes Size by Inch (diameter) Thickness: Sizes by MM (diameter) Thickness: inch. Stainless steel tubing sizes are selected based on their specific applications across a wide range of industries. McHoneInd. zfwnizjbqtjylnalzombezupjnhxxfrkheflrutrfrcbywnjqohqiltutnyaddenaahvgpghvgklmxth