Methods and devices for delivering and/or retrieving a filter fixed to a guidewire disposed within a blood vessel are disclosed. A system in accordance with the present invention comprises, an outer shaft having a proximal end, distal end and a wall defining an outer shaft lumen. The system also includes a stop mechanism disposed within the outer shaft lumen. The stop mechanism is preferably configured such that relative axial movement between the guidewire and the outer shaft may be selectively precluded.