The flat sewn bellows produced by PEI have the great advantage of being particularly robust and of having a closed parcel that is very contained in relation to the bellows run. The construction of this model takes place through a double stitching on the bellows’ wings. The cleaning of the sewn bellows from shavings and sludge is guaranteed: there are no folds of fabric that prevent it from falling onto the evacuator. The sewn gussets have a lower closed parcel than traditional heat-sealed gussets as there are no fabric folds in the corner. The range of buildable structures is practically endless. If the application on the machine requires structural rigidity, metal reinforcement and shaped intermediates can be inserted for a secure support on the rails. Bellows data: - B = Bellows width; - a = Bellows height; - d = Bellows return; - x = Fold height; - AP= Fold opening