of the filament 13 on its return trip the binding weft thread 22 passes alternately over and under the binding warp threads 18 21 in the spaces between each adjacent pair of loops 14 the second group of binding warp threads 20 and 21 disposed between the thread 18 and the thread 19 are not interengaged with the foundation weft 17 but are interlaced only with the binding weft thread 22 in a plane nearly flush with the common plane of the upper legs 14b of the successive loops 14 so that the path of the binding threads 20 and 21 presents itself to be only slightly undulated as shown in fig2 the binding weft thread 22 cooperates with the binding warp threads 18 21 in the binding the upper legs 14b in particular against displacement and thus preventing the loops 14 of the filament 13 as a whole from moving out of alignment when the fastener is subjected to bending stresses the binding weft thread 22 as this is reversed at a point close to the coupling head 14a serves to retain the outermost binding warp thread 18 against slipping along the upper leg 14b since the junction of binding weft thread 22 and foundation weft 17 is located internally of the heel or connecting portion 14d not beyond the external surface of this portion there is no thread behind the heel portion 14d which would otherwise interfer with the movement of the slider the second embodiment shown in fig3 and 4 is the same in all respects as the first embodiment which has been discussed only except for a slight modification.