Automatic self-dimensioning carton sealers with self-adhesive tape for top and bottom sealing of random American-type boxes. The machines model Gem X are ideal to seal cartons, with different dimensions in length, width and height which are randomly fed into the taping machine. The taping head and the two side belts adjust automatically to each box size. The boxes are fed by lateral conveyor belts, driven by a single motor thus optimising even sliding of the boxes and ensuring perfect alignment of the upper and lower flaps which in turn guarantees perfect sealing. These models can be used by non-specialist staff and, if combined with infeed and outfeed conveyors, represents a simple, effective and economical packing station. The machines, when combined with automatic devices for centring and regulating the flow of boxes (DAC ), can also work in lines not controlled by operatives.