NOVELTY - The matched glass-to-metal connecting device (10) comprises a glass envelope (20), a metal sleeve (30), an absorber tube, and flexible bellows. The glass envelope consists of a glass having a composition in a percent by weight on the basis of oxide content. The metal sleeve is directly bonded to the glass envelope, and has a thermal expansion coefficient of 4.89x 10-6K-1 in the temperature of 25-350 degrees C and a wall thickness of 0.5-1.5 mm. The glass envelope has a thermal expansion coefficient (4.7x 10-6K-1) that deviates from the metal sleeve's thermal expansion coefficient.    USE - The matched glass-to-metal connecting device such as a glass-to-metal joint is useful in vacuum tube collectors for solar energy collecting apparatus, a housekeeper seal design, and an X-ray tube.    ADVANTAGE - The matched glass-to-metal connecting device is economical and rapid to manufacture, and has high reliability.    DETAILED DESCRIPTION - The matched glass-to-metal connecting device (10) comprises a glass envelope (20), a metal sleeve (30), an absorber tube, and flexible bellows. The glass envelope consists of a glass having a composition in a percent by weight on the basis of oxide content. The metal sleeve is directly bonded to the glass envelope, and has a thermal expansion coefficient of 4.89x 10-6K-1 in the temperature of 25-350 degrees C and a wall thickness of 0.5-1.5 mm. The glass envelope has a thermal expansion coefficient (4.7x 10-6K-1) that deviates from the metal sleeve's thermal expansion coefficient by less than 4% in the temperature of 25-350 degrees C, and a wall thickness of 3 mm. The absorber tube is positioned within the glass envelope extending through the glass-to-metal joint. The flexible bellows form a portion of a seal between the absorber tube and the metal sleeve. The composition consists of boron trioxide (19 wt.%), alumina (8 wt.%), sodium oxide (2 wt.%), potassium peroxide (3 wt.%), barium oxide (3 wt.%), lithium fluoride (1 wt.%), and silica.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of glass-to-metal sealing joint.    Glass-to-metal sealing joint (10)    Glass envelope (20)    End portion of glass envelope (25)    Metal sleeve (30)    Outer diameter. (O.D)