shaft 42 visible in fig8 which may rotate around its own axis the first tooth 38 is coaxial to the first shaft 42 so that when the first shaft 42 rotates also the first tooth 38 rotates around itself while the second tooth 40 rotates around the first tooth 38 similarly the second fork 30 comprises a first tooth 44 and a second tooth 46 which are put side by side and are connected to a second shaft 48 visible in fig8 which may rotate around its own axis the first tooth 44 of the second fork 30 is coaxial to the second shaft 48 so that when the second shaft 48 rotates also the first tooth 44 rotates around itself while the second tooth 46 rotates around the first tooth 44 the hook device 32 comprises a support 49 on which an actuator not visible in the figures is fixed an l shaped element 50 is adjustably united to said actuator and comprises a lower portion 52 which is arranged under the strip 16 and acts as a hook for the lifting of a portion of the strip 16 the fixing of the l shaped element 50 to the actuator is obtained by means of a screw 54 that allows to vary the position of the l shaped element 50 depending on the space to be obtained between the loop 10 and the article of clothing 12 besides a first pin 56 and a second pin 58 are fixed to the support 49 and are arranged at a side of the l shaped element and above the strip 16 when the strip 16 is.