Agricultural baler of the rectangular type comprising: - a wheeled frame; - a baling chamber mounted to said frame and extending generally fore-and-aft with respect to the intended direction of movement of the baler and having an inlet opening in the lower wall thereof; - compression means mounted for reciprocation within the baling chamber and back-and-forth over the inlet opening therein for compressing successive charges of crop material fed through said inlet opening into said baling chamber to form a bale thereof; - feeder means comprising tines to stuff said charge from a feeder duct into the baling chamber, - a feeder duct communicating at one end with the inlet opening in the baling chamber and curving downwardly and forwardly there from and terminating in a lower, forwardly facing open crop receiving mouth; this feeder duct comprising upper and lower curved wall means (54, 53) of which the upper wall means comprises slots, extending generally from said crop receiving mouth to said inlet opening in the baling chamber for cooperation with said stuffer tines; wherein said baler further comprises adjusting means for setting the upper end of the upper wall means in a predetermined position; characterized in that - the lower end of the upper wall means is designed to pivot around an axis near the entry point of the feeder means into the lower end of the upper wall means; in that the upper wall means is formed by transversely spaced apart elongated wall members defining slots there between, extending generally from said crop receiving mouth to said inlet opening in the baling chamber; and in that the upper end of each of said elongated wall members, defining slots there between, is connected to an elongated connector member, positioned outside and transversal to the width of the feeder duct, comprising at least one shaft extending from said elongated connector member at at least one of its ends, the elongated connector member fixing said elongated wall members and defining the slots there between. - a wheeled frame; - a baling chamber mounted to said frame and extending generally fore-and-aft with respect to the intended direction of movement of the baler and having an inlet opening in the lower wall thereof; - compression means mounted for reciprocation within the baling chamber and back-and-forth over the inlet opening therein for compressing successive charges of crop material fed through said inlet opening into said baling chamber to form a bale thereof; - feeder means comprising tines to stuff said charge from a feeder duct into the baling chamber, - a feeder duct communicating at one end with the inlet opening in the baling chamber and curving downwardly and forwardly there from and terminating in a lower, forwardly facing open crop receiving mouth; this feeder duct comprising upper and lower curved wall means (54, 53) of which the upper wall means comprises slots, extending generally from said crop receiving mouth to said inlet opening in the baling chamber for cooperation with said stuffer tines; wherein said baler further comprises adjusting means for setting the upper end of the upper wall means in a predetermined position; - the lower end of the upper wall means is designed to pivot around an axis near the entry point of the feeder means into the lower end of the upper wall means; in that the upper wall means is formed by transversely spaced apart elongated wall members defining slots there between, extending generally from said crop receiving mouth to said inlet opening in the baling chamber; and in that the upper end of each of said elongated wall members, defining slots there between, is connected to an elongated connector member, positioned outside and transversal to the width of the feeder duct, comprising at least one shaft extending from said elongated connector member at at least one of its ends, the elongated connector member fixing said elongated wall members and defining the slots there between.