Abstract: A color CRT assembly comprises a tube having an external magnetic deflection yoke thereon. The tube includes an evacuated envelope with a substantially rectangular faceplate panel and a tubular neck connected by a funnel having a rectangular open end sealed to the faceplate panel. A three color phosphor screen is carried on an inner surface of the faceplate panel and a color selection electrode is mounted in spaced relation therefrom. An electronic gun is disposed within the neck of the tube for generating and directing at least one electron beam to the screen. The magnetic deflection yoke is located on the tube, in the region of the funnel-to-neck junction of the envelope, for subjecting the beam to magnetic fields which cause the beam to scan a rectangular raster over the screen. The assembly is improved by the inclusion, in the funnel, of a quantity of glass which attenuates x-radiation from the tube. The quantity of glass is disposed adjacent to the yoke, on the faceplate side thereof.