The invention relates to a polymer mixture, comprising a) a polymer matrix which is composed of a acrylatepolymer or of a mixture of acrylatepolymers with a Vicat softening point VSP of at least 104\xb0 C. By this arrangement, said base cannot be connected to said illumination member directly, users would not make mounting errors in use. The retention member can be formed as a sleeve or with pockets for engaging the frame member. Said piece bridges a gap between the front end regions of the front pressurised cushions, covering the upper faces of the front pressurised cushions and can be displaced in relation to the latter, so that the head of the pilot can turn freely and his or her chin is prevented from entering the gap. Accordingly, the ink jet printer head can be used for a long time in steady without deterioration of the piezoelectric member and the ink in case of using conductive ink like water ink. When \u0394NT is equal to, or less than, a preset value \u03b2, it is determined that a failure related to the neutral state of the automatic transmission has occurred.