Abstract: A bag for containing powdery or granular material having a tubular outer wall made of a flexible material and a closing and opening system arranged at one end of the tubular outer wall, as seen in a longitudinal direction of the bag, the closing and opening system including a pair of opposite angle folds extending longitudinally in line with the wall and folded laterally toward the interior of the bag, a pair of opposite lateral flaps extending longitudinally in line with the wall and folded transversely toward the interior of the bag, overlapping the angle folds in the longitudinal direction, where each lateral flap is attached to the two angle folds that it overlaps, the closing and opening system further including a bottom strip that is removably attached over the angle folds and the lateral flaps in the longitudinal direction, being oriented in the lateral direction so as to close the bag, where the bottom strip can be torn off entirely from the rest of the bag in order to open the bag, and includes a gri