A padlock comprising: - a case; - an arc having a first end and a second end and assembled in a mobile way with respect to the case between an open position and a close position; - Means (105, 150, 106, 180) to block the arc in said close position and unblock it, allowing it to turn to the open position, said means comprising a cylindrical device cooperating with a retaining device that acts on the first end of the arc, the said cylindrical device and the retaining device being both inserted in a single longitudinal channel obtained in the case, the case foreseeing two further longitudinal channels (220, 210) in which the said first and second ends of the arc are arranged in a sliding manner; - and wherein a retaining system is comprised that constrains the cylindrical device inside the cylindrical seat without impeding the rotation thereof; - the cylindrical device further integrating in itself a rotational binding device, mobile between a block position in which it engages against the cylindrical seat of the case in which it is inserted, impeding the rotation thereof of the cylindrical device with respect to the case, and an unblock position in which it disengages from the cylindrical seat, leaving the cylindrical device free to rotate, the case being realized in a single piece; - said retaining system being in the shape of a ring cooperating with the cylindrical seat in which it is inserted, said case being lacking in transversal holes and small pistons inserted in said transversal holes to intercept the cylindrical device, and wherein the second end of the arc comprises a ring cooperating with the seat in which it is inserted in a such a way as to slide of a predetermined quantity and contextually resulting impeded from separating from the case, the case and the arc having a superficial coating obtained with an operation of galvanization of the case and of the arc coated separately before being assembled. - a case; - an arc having a first end and a second end and assembled in a mobile way with respect to the case between an open position and a close position; - Means (105, 150, 106, 180) to block the arc in said close position and unblock it, allowing it to turn to the open position, said means comprising a cylindrical device cooperating with a retaining device that acts on the first end of the arc, the said cylindrical device and the retaining device being both inserted in a single longitudinal channel obtained in the case, the case foreseeing two further longitudinal channels (220, 210) in which the said first and second ends of the arc are arranged in a sliding manner; - and wherein a retaining system is comprised that constrains the cylindrical device inside the cylindrical seat without impeding the rotation thereof; - the cylindrical device further integrating in itself a rotational binding device, mobile between a block position in which it engages against the cylindrical seat of the case in which it is inserted, impeding the rotation thereof of the cylindrical device with respect to the case, and an unblock position in which it disengages from the cylindrical seat, leaving the cylindrical device free to rotate, the case being realized in a single piece; - said retaining system being in the shape of a ring cooperating with the cylindrical seat in which it is inserted, said case being lacking in transversal holes and small pistons inserted in said transversal holes to intercept the cylindrical device, and wherein the second end of the arc comprises a ring cooperating with the seat in which it is inserted in a such a way as to slide of a predetermined quantity and contextually resulting impeded from separating from the case, the case and the arc having a superficial coating obtained with an operation of galvanization of the case and of the arc coated separately before being assembled.