Abstract: An apparatus for testing an hermetic, glass-like frit seal interposed between the funnel and faceplate of an in-process cathode ray tube is disclosed. A discontinuity in the hermetic seal causes a high voltage breakdown in the seal when a test voltage is applied to the cathode ray tube. The apparatus comprises an elastomeric band which is capable of being stretched over the tube, conforming to the shape of the hermetic seal between the funnel and faceplate. The apparatus also comprises band-mounting means which holds the elastomeric band and stretches the band to fit around the hermetic seal such that the band forms electrical and mechanical contact with the frit seal. The improvement comprises electrically conductive spring means embracing the elastomeric band at its periphery. The spring means are attached to the band mounting means for stretching and relaxing in concert with the elastomeric band.