Medical devices and systems for treating a vascular condition are described. One such device (10) includes a sheath (12), an elongate delivery member (29), and a lock (26). The sheath has a wall that includes an inner surface and an outer surface. The inner surface defines a lumen (14) along the sheath. An access opening (30) is in a proximal portion of the wall and is in fluid communication with the lumen. The delivery member is at least partially disposed within the lumen. The delivery member passes through the access opening. The lock is slidably disposed on an outer periphery of the wall. The lock slidably moves from a first position (22) to a second position (24) along a longitudinal axis of the sheath. The lock positioned in the first position restricts movement of the delivery member.
