FRP Rectangular Tube, (IPE) Isophthalic Polyester Non-Flame Retardant, 4" x 2", 1/8" x 1/4" Wall Thickness, Olive Green - Harrington Industrial Plastics
Amazon.com: Rectangle Black Plastic Plug End Cap - 1" x 1/2” Rectangular Tube Caps - Rectangle Tubing End Cap Plug - Plastic Plugs for Rectangular Tube - Rectangular Hole Plug - Rectangular