A device for harvesting long agricultural products such as grass, straw, legumes, biomass products and the like, of the type which can be pulled by a pulling vehicle, comprising: - a frame having a main axis of extension which, during use, is kept transversal to the axis of movement of the pulling vehicle: - a plurality of agricultural product harvesting elements, each in turn equipped with at least one long harvesting prong; - a movement system for moving each of the harvesting elements along a closed trajectory surrounding the main axis of extension, where the closed trajectory comprises a stretch for conveying the agricultural product between a point where the product is picked up from the ground by the long prongs and a point where the agricultural product is released by the prongs; - a plurality of bands fixed to the frame, arranged one after another along the main axis of extension and spaced out in such a way that each harvesting element is at least partly interposed between two bands located one after the other, - a conveyor unit comprising an elongate body extending along its own axis of rotation (C, and provided with at least one peripheral step forming an agricultural product feed shoulder extending, along an axis which is substantially radial relative to said axis of rotation, between an edge proximal to the axis of rotation and an edge distal from the axis of rotation; said conveyor unit 1 being located close to the release point and positioned in such a way that its axis of rotation is aligned with said main axis of extension of the frame, positioned at a height such that the elongate body is at least partly projecting above an end stretch of each band and located at the release point characterised in that it comprises movement means designed for rotating the elongate body about the axis of rotation with alternating motion in a first direction and a second direction which are opposite to one another. - a frame having a main axis of extension which, during use, is kept transversal to the axis of movement of the pulling vehicle: - a plurality of agricultural product harvesting elements, each in turn equipped with at least one long harvesting prong; - a movement system for moving each of the harvesting elements along a closed trajectory surrounding the main axis of extension, where the closed trajectory comprises a stretch for conveying the agricultural product between a point where the product is picked up from the ground by the long prongs and a point where the agricultural product is released by the prongs; - a plurality of bands fixed to the frame, arranged one after another along the main axis of extension and spaced out in such a way that each harvesting element is at least partly interposed between two bands located one after the other, - a conveyor unit comprising an elongate body extending along its own axis of rotation (C, and provided with at least one peripheral step forming an agricultural product feed shoulder extending, along an axis which is substantially radial relative to said axis of rotation, between an edge proximal to the axis of rotation and an edge distal from the axis of rotation; said conveyor unit 1 being located close to the release point and positioned in such a way that its axis of rotation is aligned with said main axis of extension of the frame, positioned at a height such that the elongate body is at least partly projecting above an end stretch of each band and located at the release point