fig3 shows that the entire torsion spring 25 is or can be confined in that portion of the bore 17 which extends into the mandrel 13 the u shaped terminal portion 21 engages the intermediate portion of the post 23 and the rightmost convolution 26 of the spring 25 is integral with the aforementioned leg 35 the leg 35 extends from the bore 17 at the exposed side of the end wall 37 and has a 90 degree bend to extend substantially radially outwardly and to merge into the tooth shaped loop catcher 33 the section 31 between the loop catcher 33 and the end portion 59 is or can be substantially straight and extends substantially radially of the hook 11 the section 29 between the end portion 59 and the leg 34 also extends substantially radially of the hook 11 and merges into the leg 34 which latter extends into the bore 17 and into the interior of the torsion spring 25 those portions of the legs 34 35 which are located in the bore 17 are or can be at least substantially parallel to the axis a the end portion 59 is a loop which makes an angle of approximately 180 degrees so that the sections 29 and 31 of the loop engaging member 27 are or can be substantially parallel to each other at the inner side of the end wall 37 the loop catcher 33 can be located substantially midway between the end portion 59 and the nearest portion of the bore 17 in the hook 11 the loops of the needle thread 53 can move the end portion 59 and hence the entire loop engaging member 27 relative to the hook 11 in the aforementioned vertical plane next.