around the inner proximal surface of the sleeve 140 referring to fig6 a and fig6 b as the first groove 113 moves in a proximal direction toward the rear lug 144 the hub 110 surface on either side of the first groove 113 is supported by the three inner ribs 151 this allows the hub 110 to pass smoothly through the proximal portion of the sleeve 140 as the first groove 113 passes through the proximal end of the sleeve and under the rear lug 144 the 3 inner ribs 151 prevent the first groove 113 from engaging the rear lug 144 as the hub 110 continues to be drawn in the proximal direction the sleeve 140 is now also drawn in the proximal direction due to the abutment of the second annular ring 112 with the three inner ribs 151 it should be noted that the second annular ring 112 which is aligned next to but proximal of the first annular ring 111 on the hub 110 includes a sloped surface that tapers in the proximal direction the hub 110 is drawn in the proximal direction until the sheath 130 is engaged in a final locking position in which the sheath 130 becomes unreleasably locked to the.