identified by numeral references a hook body 2 comprising a cylindrical cavity 11 which in the example shown has a central hole 17 fig2 suitable to receive a shaft omitted for the sake of simplicity of the graphic representation from which the hook 1 receives motion in a different embodiment of which the graphical representation is omitted the shaft is integral with the hook 1 a basket 6 free to rotate within the cylindrical cavity 11 to which it is constrained by a rib 14 formed on the outer surface of the basket 6 and comprising a well 18 of the basket 6 in which is housed the bobbin case 8 complete with bobbin 4 an inner diameter 19 delimiting said well 18 of the basket 6 in which fits the external diameter 20 of the bobbin case 8 a projection 21 on the inner diameter 19 of said well 18 of the basket 6 that coupling with the guide 22 in the figures are indicated with 22 the edges of said guide on the outer diameter 20 of the bobbin case 8 allows the angular reference of the bobbin case for the correct mounting of the bobbin case 8 in the basket 6 a possible post 23 into which the hole 24 of the shaft 25 fig2 of the bobbin case 8 is inserted a race 10 formed in the inside wall of the cylindrical cavity 11 of the hook body 2 and delimited by two plane surfaces parallel with each other and by a cylindrical surface perpendicular to the plane ones in which the rib 14 of the basket 6 engages to prevent the axial and radial translation of the.