Wrapping apparatus associable with a packaging machine, in particular a bundling machine, for wrapping with a film made of plastic material groups of products, comprising: - conveyor means (21, 22, 23) for supporting and moving said groups of products along a longitudinal advancing direction and forming a supporting plane of said products; - a feeding unit of the film positioned under said supporting plane for dispensing film portions of defined length through a transverse opening of said conveyor means (21, 22, 23) so as to engage said groups of products; - a wrapping unit comprising a plurality of crossbars, each of which supported by at least a respective rod, said crossbars being arranged for picking said film portions coming out from said transverse opening and wrapping said film portions around said groups of products, hub means rotatable around a rotation axis and slidably supporting said rods of said crossbars so that said rods are mobile linearly and transversally to said rotation axis and rotatably around said rotation axis, said crossbars being consequently moved along a defined closed loop wrapping trajectory; and - guiding means (6, 7) engaged by said rods and/or by said crossbars for guiding the latter ones along said wrapping trajectory changing a distance of said crossbars from said rotation axis during a rotation of said respective rods; said apparatus being characterized in that said rods are coupleable in a removable manner to said hub means so as to change a number of said rods and of said respective crossbars and an angular distance between said rods around said rotation axis according to dimensions of products and/or a pitch (p) between successive groups of products on said supporting plane, wherein - each crossbar is fixed to an end portion of a respective rod that is removably connected to said hub means by means of a respective supporting arm suitable to slidably support said rod transversely, in particular orthogonally, to said rotation axis, - said hub means comprises a central body that is rotatably connected to frame means of said wrapping unit around said rotation axis and comprises fastening means for removably fastening a desired number of supporting arms for respective rods, said fastening means comprising a plurality of fastening elements, which are mutually angularly spaced around said rotation axis, a supporting arm being reversibly fixed to a the respective fastening element - conveyor means (21, 22, 23) for supporting and moving said groups of products along a longitudinal advancing direction and forming a supporting plane of said products; - a feeding unit of the film positioned under said supporting plane for dispensing film portions of defined length through a transverse opening of said conveyor means (21, 22, 23) so as to engage said groups of products; - a wrapping unit comprising a plurality of crossbars, each of which supported by at least a respective rod, said crossbars being arranged for picking said film portions coming out from said transverse opening and wrapping said film portions around said groups of products, hub means rotatable around a rotation axis and slidably supporting said rods of said crossbars so that said rods are mobile linearly and transversally to said rotation axis and rotatably around said rotation axis, said crossbars being consequently moved along a defined closed loop wrapping trajectory; and - guiding means (6, 7) engaged by said rods and/or by said crossbars for guiding the latter ones along said wrapping trajectory changing a distance of said crossbars from said rotation axis during a rotation of said respective rods; - each crossbar is fixed to an end portion of a respective rod that is removably connected to said hub means by means of a respective supporting arm suitable to slidably support said rod transversely, in particular orthogonally, to said rotation axis, - said hub means comprises a central body that is rotatably connected to frame means of said wrapping unit around said rotation axis and comprises fastening means for removably fastening a desired number of supporting arms for respective rods, said fastening means comprising a plurality of fastening elements, which are mutually angularly spaced around said rotation axis, a supporting arm being reversibly fixed to a the respective fastening element