Abstract: An apparatus for controlling the lateral displacement of at least one material web, comprising one roller pivoting about a shaft, which roller comprises laths that extend in the direction of the shaft and that are arranged in circumferential direction of the roller, whereas each lath is mounted in such a way that it can be moved in the direction of the shaft. Furthermore the roller comprises at least one lath guiding device on which the movable laths are guided, whereas the lath guiding device comprises for each lath a respective region for guiding each individual lath. According to the invention the roller comprises at least one lath securing device which is used to protect the laths from being detached from the apparatus when the region for guiding the respective lath is defective, whereas the lath securing device comprises for each lath a respective region for securing each individual lath.