A model of a telescopic boom including at least three tubular sections arranged in a row one after another and an outer cross-section of which becomes smaller from a tubular section to a tubular section in a direction toward a free end of the telescopic boom, with each of the tubular sections forming, at its front end, a cut-out into which a bar provided at a rear end of a preceding, in the direction toward the free end of the telescopic boom, tubular section, projects in a pull-out condition of the telescopic boom, with the front bar surface of a bar projecting, in the pull-out condition of the boom, beyond the cut-out, and with the rear abutment edge of the cut-out facing the rear surface of the bar.