A roller comprising a replaceable sleeve and a hub assembly for mounting said roller on a shaft of an apparatus having a rotation axis (X-X), said sleeve having a body defined by an outer peripheral surface and an inner peripheral surface connected to each other by means of a first base surface and a second base surface perpendicular to said axis (X-X), said hub assembly comprising a hollow body open along said axis (X-X), said hollow body being adapted to engage said inner peripheral surface of said sleeve and being further adapted to receive at least a bearing into its cavity wherein said sleeve further comprises at least a first recess and at least a second recess formed respectively on said first base surface and on said second base surface , said at least a first recess and said at least a second recess extending parallel to said axis (X-X) inside the body of said sleeve and spaced from said outer peripheral surface and said inner peripheral surface , and said hub assembly further comprises a first flange and a second flange centrally drilled to receive said shaft and, furthermore, said first flange and said second flange being adapted to engage the openings of said cavity of said hollow body , characterized in that said first flange and said second flange being provided, respectively, with at least a first extension and at least a second extension extending parallel to said axis (X-X) and radially spaced from said hollow body , said at least a first extension and said at least a second extension being adapted to respectively engage said at least a first recess and said at least a second recess of said sleeve . said sleeve having a body defined by an outer peripheral surface and an inner peripheral surface connected to each other by means of a first base surface and a second base surface perpendicular to said axis (X-X), said hub assembly comprising a hollow body open along said axis (X-X), said hollow body being adapted to engage said inner peripheral surface of said sleeve and being further adapted to receive at least a bearing into its cavity wherein said sleeve further comprises at least a first recess and at least a second recess formed respectively on said first base surface and on said second base surface , said at least a first recess and said at least a second recess extending parallel to said axis (X-X) inside the body of said sleeve and spaced from said outer peripheral surface and said inner peripheral surface , and said hub assembly further comprises a first flange and a second flange centrally drilled to receive said shaft and, furthermore, said first flange and said second flange being adapted to engage the openings of said cavity of said hollow body , characterized in that said sleeve further comprises at least a first recess and at least a second recess formed respectively on said first base surface and on said second base surface , said at least a first recess and said at least a second recess extending parallel to said axis (X-X) inside the body of said sleeve and spaced from said outer peripheral surface and said inner peripheral surface , and said hub assembly further comprises a first flange and a second flange centrally drilled to receive said shaft and, furthermore, said first flange and said second flange being adapted to engage the openings of said cavity of said hollow body , characterized in that said first flange and said second flange being provided, respectively, with at least a first extension and at least a second extension extending parallel to said axis (X-X) and radially spaced from said hollow body , said at least a first extension and said at least a second extension being adapted to respectively engage said at least a first recess and said at least a second recess of said sleeve . <EOS>