In some examples, a catheter defines a longitudinal axis and includes an inner member, a retaining member, and a support member. The inner member has an outer wall, and a portion of the inner member has a first stiffness. The retaining member defines a pocket configured to receive a connecting member of an expandable medical device. The retaining member has a second stiffness that is different from the first stiffness. The support member extends distally from the retaining member. In some examples, the support member is configured to be received radially within the expandable medical device when the connecting member is received within the pocket. The support member is configured to provide a gradual transition between the first stiffness of the inner member and the second stiffness of the retaining member.