A cylindrical container rotatable about its axis and containing a substance having rheological properties, the cylindrical container comprising a rheological probe unit (10, 110,210) comprising: a base (11,118) arranged so as to be mountable in a wall of the cylindrical container; a resistance member extending from the base (11,118), arranged so as to be in a radial orientation when the base (11,118) is mounted to the cylindrical container, and onto which, when the unit is in use, a normal resistance pressure is imparted by the rheological substance when the resistance member is submerged and moved therein by the rotation of the cylindrical container; characterised in that: a force sensor adapted to provide force values indicative of the resistance pressure at given points in time; a speed sensor adapted, when the unit is in use, to provide speed values indicative of the speed at which the resistance member is moved in the substance at given points in time, in both a low speed range and a high speed range; a power source; a rheological value calculator powered by said power source and adapted to obtain a calculated value indicative of at least one of said rheological properties of the substance using at least one of both: a force value and speed value in the low speed range corresponding to a given point in time; and a force value and speed value in the high speed range corresponding to an other given point in time; and an emitter. a base (11,118) arranged so as to be mountable in a wall of the cylindrical container; a resistance member extending from the base (11,118), arranged so as to be in a radial orientation when the base (11,118) is mounted to the cylindrical container, and onto which, when the unit is in use, a normal resistance pressure is imparted by the rheological substance when the resistance member is submerged and moved therein by the rotation of the cylindrical container; characterised in that: a force sensor adapted to provide force values indicative of the resistance pressure at given points in time; a speed sensor adapted, when the unit is in use, to provide speed values indicative of the speed at which the resistance member is moved in the substance at given points in time, in both a low speed range and a high speed range; a power source; a rheological value calculator powered by said power source and adapted to obtain a calculated value indicative of at least one of said rheological properties of the substance using at least one of both: a force value and speed value in the low speed range corresponding to a given point in time; and a force value and speed value in the high speed range corresponding to an other given point in time; and an emitter. a force sensor adapted to provide force values indicative of the resistance pressure at given points in time; a speed sensor adapted, when the unit is in use, to provide speed values indicative of the speed at which the resistance member is moved in the substance at given points in time, in both a low speed range and a high speed range; a power source; a rheological value calculator powered by said power source and adapted to obtain a calculated value indicative of at least one of said rheological properties of the substance using at least one of both: a force value and speed value in the low speed range corresponding to a given point in time; and a force value and speed value in the high speed range corresponding to an other given point in time; and an emitter. a force value and speed value in the low speed range corresponding to a given point in time; and a force value and speed value in the high speed range corresponding to an other given point in time; and an emitter.