Epicyclic handwheel for a valve, in particular a quarter-turn valve, comprising: - a control knob with an inner surface and an outer surface situated opposite each other with respect to a longitudinal axis (X-X), the control knob being rotationally operable about the longitudinal axis; - an epicyclic mechanism for transmission of a rotational movement, comprising: -- a sun gear extending along the longitudinal axis (X-X) and rotationally integral with the inner surface of the control knob; -- a planet carrier configured to be made rotationally integral with a shaft of the valve; -- a crown wheel configured to be made rotationally integral with a body of the valve and provided with an internal annular toothing coaxial with the sun gear; -- a plurality of planet gears mounted on the planet carrier and arranged to rotate about a respective axis parallel to the axis of the sun gear and mesh with said sun gear and with the internal annular toothing of the crown wheel; so that by rotationally operating the control knob the rotational movement of the sun gear is transmitted to the planet carrier and therefore to the valve shaft; and further comprising an annular plate arranged between the planet gears and the control knob and rotationally integral with the planet carrier, the annular plate having on its front surface, adjacent to the inner surface of the control knob, an indication of the value of at least one operating parameter (α; Kv) of the valve; and wherein the control knob has at least one window (130;132) on its front surface which allows viewing of at least one operating parameter (α; Kv) indicated on the annular plate; characterized in that the indication on the front surface of the annular plate comprises a plurality of graduated scales indicating different values of at least one same parameter which is variable depending on the type and/or size of the valve; and in that the handwheel further comprises an element for partially covering a window (130;132) of the control knob, which may be stably and reversibly connected to the control knob, and is configured to provide a respective reduced size window able to show only one or more of the graduated scales indicated on the annular plate to allow the viewing only of indications relating to one or more parameters of interest or relating to a specific type and/or size of valve. - a control knob with an inner surface and an outer surface situated opposite each other with respect to a longitudinal axis (X-X), the control knob being rotationally operable about the longitudinal axis; - an epicyclic mechanism for transmission of a rotational movement, comprising: -- a sun gear extending along the longitudinal axis (X-X) and rotationally integral with the inner surface of the control knob; -- a planet carrier configured to be made rotationally integral with a shaft of the valve; -- a crown wheel configured to be made rotationally integral with a body of the valve and provided with an internal annular toothing coaxial with the sun gear; -- a plurality of planet gears mounted on the planet carrier and arranged to rotate about a respective axis parallel to the axis of the sun gear and mesh with said sun gear and with the internal annular toothing of the crown wheel; -- a sun gear extending along the longitudinal axis (X-X) and rotationally integral with the inner surface of the control knob; -- a planet carrier configured to be made rotationally integral with a shaft of the valve; -- a crown wheel configured to be made rotationally integral with a body of the valve and provided with an internal annular toothing coaxial with the sun gear; -- a plurality of planet gears mounted on the planet carrier and arranged to rotate about a respective axis parallel to the axis of the sun gear and mesh with said sun gear and with the internal annular toothing of the crown wheel; so that by rotationally operating the control knob the rotational movement of the sun gear is transmitted to the planet carrier and therefore to the valve shaft; and further comprising an annular plate arranged between the planet gears and the control knob and rotationally integral with the planet carrier, the annular plate having on its front surface, adjacent to the inner surface of the control knob, an indication of the value of at least one operating parameter (α; Kv) of the valve; and wherein the control knob has at least one window (130;132) on its front surface which allows viewing of at least one operating parameter (α; Kv) indicated on the annular plate; characterized in that the indication on the front surface of the annular plate comprises a plurality of graduated scales indicating different values of at least one same parameter which is variable depending on the type and/or size of the valve; and in that the handwheel further comprises an element for partially covering a window (130;132) of the control knob, which may be stably and reversibly connected to the control knob, and is configured to provide a respective reduced size window able to show only one or more of the graduated scales indicated on the annular plate to allow the viewing only of indications relating to one or more parameters of interest or relating to a specific type and/or size of valve.