Spring stainless steel, PEI powder sprayed on the surface, golden yellow on the back. Our PEI bed is flexible, removable, and pei sheet can stick to magnetics very well. High strength and heat resistance. The flexible surface of the ender 3 Pro PEI bed can easily be cut to any dimension making it perfect for all build sizes and all FDM printer models.No more tape, no more glue, no more shovel, and release your printing anxiety. The PEI spring steel 235x235 is easy to adhere to the printing surface, easy to remove the prints and flex slightly to pop your print right off. Our Ender 3 PEI build plate is used in a 3D printing application, PEI is excellent because it can withstand the numerous heat cycles that a 3D print bed goes through from print to print.