Rectangular Tubing is manufactured from isophthalic polyester resin and glass mat into a pultruded composite form. EXTREN - Series 525 profiles have a synthetic resin rich veil that contains a UV inhibitor and corrosion resistant surface. Flammability is rated as self-extinguishing. These profiles are non-magnetic and exhibit good electrical and thermal insulation properties that are transparent to radio waves and EMI/RFI transmissions.EXTREN is 30 Percent lighter and has 86 Percent of the yield strength of aluminum. It is pound for pound stronger than aluminum in the lengthwise direction of the profile. Temperatures above 150 F (65 C) are not recommended. These profiles can be easily fabricated with carpentry or metal working tools. Fasten with screws, bolts, and rivets, or join with adhesives.