1、These spring tube are made of spring steel, which is heat‑resistant, corrosion‑resistant, and has good relaxation resistance. 2、These tube have super elasticity and will not be deformed no matter how they bend during use. 3、Provide 5 kinds of spring pipe with different diameters, which can meet your diversified needs. 4、These spring tube can be used with pipe benders to obtain better results and are also good replacement parts. 5、These spring tube can be used for copper pipes, aluminum pipes, thin‑walled steel pipes, etc., bringing a lot of convenience to your life. 5 x Bender Spring Item Type: Bender SpringMaterial: Spring steelSpecification:1/4in: Length: Approx. 200mm / 7.9in, outer diameter: Approx. 9mm / 0.4in, inner diameter: Approx. 7mm / 0.3in5/16in: Length: Approx. 205mm / 8.1in, outer diameter: Approx. 10mm / 0.4in, inner diameter: Approx. 8.5mm / 0.3in3/8in: Length: Approx. 200mm / 7.9in, outer diameter: Approx. 12.5mm / 0.5in, inner diameter: Approx. 10mm / 0.4in1/2in: Length: Approx. 207mm / 8.1in, outer diameter: Approx. 16mm / 0.6in, inner diameter: Approx. 13.5mm / 0.5in5/8in: Length: Approx. 200mm / 7.9in, outer diameter: Approx. 19.5mm / 0.8in, inner diameter: Approx. 16.5mm / 0.6in