A filter for the filtration of media, having a pleated, cylindrical filter element, which is located between a perforated, cylindrical backflow preventer and a perforated, cylindrical core, the filter element being arranged in pleated folds, a plurality of folds having a first fold height which is greater than the difference between the radius of the backflow preventer and the radius of the core and which, each being inclined in relation to a radial line by an angle of inclination, are directed away from the outer surface of the core, a plurality of folds being provided having at least one second shorter fold height, and the folds of the second shorter fold height being arranged adjacent, radially at the outside, to the backflow preventer and alternatingly adjacent to the folds of the first fold height.