The utility model provides a voltage transformer secondary air switch caliper type marks tablet, side opening cell type card that includes an upper end cardboard elastically stretchable with connect in the marking of the cell type card back tablet (2), the cell type card includes L shape backup pad (1a) and the upper end cardboard (1b) of cartridge at L shape backup pad riser top, during the vertical tensile pole (1c) of upper end cardboard through two parallels inserts the jack on the backup pad riser, is fixed with spring (1d) bottom in the jack, and the spring top is connected with the pole bottom of drawing, L shape backup pad and upper end cardboard and mark the tablet and all adopt insulating plastic to manufacture. The utility model discloses the installation is firm, safe and reliable, the light small and exquisite and installation of being convenient for.