Abstract: A medical device system may include a sheath, a pusher wire, and a locking element. The pusher wire may be slidably disposed within a lumen of the sheath. The locking element may have a proximal end, a distal end, an intermediate region disposed between the proximal end and the distal end, and a lumen extending from the proximal end to the distal end. The locking element may have a first inner diameter adjacent to the distal end and a second inner diameter adjacent to the proximal end, the second inner diameter smaller than the first outer diameter. The distal end region of the locking element may be configured to freely slide over the sheath and when a proximal end region of the locking element is disposed over the sheath, the locking element may be configured to depress the sheath radially inwards.