Abstract: Techniques of this disclosure relate to delivery devices for use in delivering a prosthesis via percutaneous transcatheter (or transluminal) techniques. Embodiments achieve variable tensile and bending resistance of a transcatheter delivery device, which improves trackability and positioning accuracy of the system while maintaining the tensile characteristics of the transcatheter delivery device required for recapture and deployment of the prosthesis. Other embodiments relate to other components of a transcatheter delivery device that can be torqueable to assist in rotational positioning of the prosthesis. Other embodiments relate to the capsule of the transcatheter delivery device outer sheath member and/or the prosthesis retention member of the transcatheter delivery device that can passively or otherwise rotate about their respective central axis to prevent built-up torque during delivery of a prosthesis. The capsule can include an echogenic marker.