from the needle cover 22 any alternative mechanism to the detent can be used as long as it functions to lock into the final position as described above the l shaped or other shaped end of the stop bar and such that there is preferably a minimum of frictional drag during catheter insertion for example fig1 and 19 illustrate alternative embodiments of the configurations for the needle cover and the stop mechanism another aspect of the present invention is illustrated in fig9 13 in which means are provided for rotatably attaching at least one of the needle case and the stop assembly in relation to the needle cover so that the needle cover and the catheter hub as a unit is rotatable around the axis of the needle particularly when inserting the cannula into the patient for example with reference to fig9 therein illustrated are catheter hub 18 and a needle cover 122 needle cover 122 includes a disk shaped bottom portion 123 having an outwardly extending flange 125 the stop assembly includes a stop bar 142 having a disk shaped member 160 having an upwardly extending portion 162 with an inwardly extending flange 164 which is attachable to outwardly extending flange 125 of needle cover 122 for example in a snap fit manner in this configuration the bottom portion of the needle cover and the disk shaped member of.