A collapsible medical device for use, e.g., as a vascular filter. The device includes a mandrel having a distal end and a stop spaced proximally of the distal end. A proximal length of the mandrel extends proximally of the stop and a distal length of the mandrel extends distally of the stop. A functional element (e.g., a vascular filter) has a radially expandable body and includes a proximal slider and a distal slider. The proximal and distal sliders are slidable along the mandrel independently of one another such that the distance between the proximal slider and distal slider can be varied to effect different configurations of the functional element. In one method of using such a device, the functional element is urged distally to a treatment site by urging the mandrel distally. This causes the stop to exert a distal biasing force on the distal slider, which acts against a restorative force of the functional element to axially elongate the functional element and reduce friction between the functional element and a wall of the vessel.
