Pultruded glass fiber reinforced structural shapes and plate are electrically and thermally non-conductive, impact resistant, and EMI/RFI transparent. Square tubes are a great option for your structural needs. They can be up to 4″ wide., Pultruded Fiberglass Square Tubing backSTORY: Pultruded fiberglass Square Tubing is manufactured through a process that combines continuous glass fibers and resin, resulting in a strong, lightweight, and corrosion-resistant material., Pultruded Fiberglass Tubing is a corrosion resistant structural shape that outlasts traditional building materials like steel and even stainless steel tube. Most corrosive environments will benefit from using either square or round FRP tubing in a wide variety of situations., , , .