These are friction fit brackets to replace the stock LEDs with white ones and to put them at an angle and height that actually lets you see the work space. The LEDs I used were from Alpena. They come in a Strip and each section is 50mm. But really any led strip 10mm wide or less should work. The left and right bracket are not interchangeable because the part that friction fits to the case is wider at the top than the bottom to match the chassis of the robo3d printer. Also the LEDs are angled inward at 45 degrees to get the light on the work surface. Because these are tall and narrow it might work better to print both at once. Just position them close to each other on the bed. It also cuts down on the total print time.