This device is used for testing the elongation and permanent deformation of the insulation layer of electric wires and cables under the simultaneous action of heating and load, as specified in GB/T2951.21-2008 "General Test Methods for Insulating and Sheathing Materials of Electric Cables - Part 21: Special Test Methods for Elastomer Blends - Thermal Elongation Test", to determine its thermal elongation performance. This device is made of stainless steel, which extends its service life. Its appearance is only designed with an inch root lift aging box heating system, The bracket size is 430x200x400, ensuring that the device can be freely placed in the old box to achieve accurate test results and convenient operation