All steel under frame structure. Applied all steel under frame structure, greatly enhance stability of the machine while working. Processed with welding tempering treatment and aging treatment on square tube, make sure under frame and platform are not be deformed with time, highly extended printer lifespan and its accuracy. Equipped print head height adjustment for media, it enables print head auto-adjust with media thickness under 100mm, deliver a smooth printing even with various media. Anti-collision system for print head.