TTriActive USA’s TCHI Assumes usage of American standard size tubing, namely 4” x 4” square tubing x ¼ wall, 1-1/2” x 3” rectangular tubing x 11ga, 2×2 sq tube 11ga, 2” Sch. 80 pipe, ¼” hot rolled flat stock. TriActive USA Fitness Equipment does not include any of the following: exposed cables, hydraulics or plastic seating.