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 (312, 320) 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 (312, 320) 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 (312, 320) 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.