Premium Tube Inserts 1 Inchx14 RH (1.5 Inch, 1/8 Inch Wall Square Tubing) These are our premium square tube inserts. We offer them for 2×2 1/4 square tubing and 1.5×1.5, 1/8 square tubing. They are all CNC machined for a press fit into the desired tube. We press them in with a hydraulic ram, however a 5 lb sledge hammer will knock them in. Once you press them in, check to make sure they are square, then fully weld them.