Has side arm with auxiliary discharge for pressure adjustment, focus cathode, anode and long side arm with X-ray transmitting glass end. Uses a curved cathode to focus the electron beam onto a tungsten anode. The tube has a high lead content to absorb X-rays except for a small transmission window at the end of a long tube. The combination of small source on the anode and small window at the end of the tube produced a collimated beam. Primarily used in crystallography, x-ray spectroscopy, and radiography.