Portable device (100; 200; 300; 400; 500) for measuring or controlling the tensile force in a strap for the lashing of a load, comprising: a first abutment element (1 1; 1A 1; 1B 1; 1C 1; 1D 1) and a second abutment element (1 2; 1A 2; 1B 2; 1C 2; 10D 2), which are arranged in a first plane, and which, in position of use for measuring or controlling the tensile force, come into contact with a side of a strap, which forms a lower side facing the load, a third element (3; 3A; 3B; 3C; 3D), which comprises a pressure-sensitive means, which, in position of use, is actuated by, or come into contact with, an upper side of a strap facing away from the load, whereby said first (1 1; 1A 1; 1B 1 1C 1, 1D 1) and second abutment elements (1 2; 1A 2; 1B 2; 1C 2; 10 2) are arranged at the same distance from, and symmetrically in relation to, said third element (3; 3A; 3B; 3C; 3D), and that said first and second abutment elements (1 1; 1 2; 1A 1; 1A 2; 1B 1; 1B 2; 1C 1; 1C 2; 1D 1; 1D 2) are connected to first and second outer end portions (2 11; 2 12), respectively, of a first and second connecting elements (2 1; 2 2; 2A 1; 2A 2; 2B 1; 2B 2; 2C 1; 2C 2; 2D 1; 2D 2), which have first and second inner end portions, respectively, which are connected to said third element (3; 3A; 3B; 3C; 3D), that said first and second abutment elements have first and second outer, free end portions respectively, which extend parallel to one another in said first plane and which point in substantially opposite directions, and that the first and second outer end portions (2 11; 2 12;) of the connecting elements are arranged to form a first and a second intermediate portion, respectively, whereby there is a transition from the connecting elements, which at least partially are located in a second plane, to the abutment elements in said first plane, whereby said first intermediate portion forms a first angle, so that a first longitudinal lateral edge of a strap can be surrounded in the transition, and that said second intermediate portion forms a second angle directed in opposite direction in relation to said first angle, so that a second longitudinal lateral edge of a strap, which is opposite to said first lateral edge, can be surrounded in the transition, and that the pressure-sensitive means (4; 4D, 54) and indication members (5; 5D) provide information relating to the current tensile force in the strap, characterized in that the pressure-sensitive means (4; 4D) comprises: a spring loaded (7; 7D) base element (8; 8D), which is slidably arranged in a housing (6; 6D), and which exhibits a protruding contacting member (9; 9D) which in position of use is adapted to come into contact with an upper side of the strap and press the base element (8; 8D) against the action of the spring (7; 7D), so that the base element (8; 8D) is pushed upwards in the housing depending on the current tensile force in the strap, that the base element (8; 8D), at the end opposite to the contacting member (9; 9D), is provided with indication element (11; 11D) which forms or is comprised by said indication member (5; 5D), and that the indication element comprises markings on the upper part of the base element or in the casing, or that indication member is electronically coupled to the pressure-sensitive means and is designed to provide information electronically, by means of a LED display or in another way visually or acoustically, about the current tensile force, and that the pressure-sensitive means(4D; 54) comprises a base member or a piston with a central hole for taking up a battery, a contact spring adapted to be in contact with a magnet and with one end of the battery and a sensor, comprising a printed circuit board, and that the sensor is adapted to sense the magnetic field or magnetic field generated by the magnet variations when the piston or base member is displaced due to a force excerted by the strap on the base element or piston, and that the sensor is connected to an indicating means comprising a LED display. a spring loaded (7; 7D) base element (8; 8D), which is slidably arranged in a housing (6; 6D), and which exhibits a protruding contacting member (9; 9D) which in position of use is adapted to come into contact with an upper side of the strap and press the base element (8; 8D) against the action of the spring (7; 7D), so that the base element (8; 8D) is pushed upwards in the housing depending on the current tensile force in the strap, that the base element (8; 8D), at the end opposite to the contacting member (9; 9D), is provided with indication element (11; 11D) which forms or is comprised by said indication member (5; 5D), and that the indication element comprises markings on the upper part of the base element or in the casing, or that indication member is electronically coupled to the pressure-sensitive means and is designed to provide information electronically, by means of a LED display or in another way visually or acoustically, about the current tensile force, and that the pressure-sensitive means(4D; 54) comprises a base member or a piston with a central hole for taking up a battery, a contact spring adapted to be in contact with a magnet and with one end of the battery and a sensor, comprising a printed circuit board, and that the sensor is adapted to sense the magnetic field or magnetic field generated by the magnet variations when the piston or base member is displaced due to a force excerted by the strap on the base element or piston, and that the sensor is connected to an indicating means comprising a LED display.