Abstract: An endovascular prosthesis (10) includes first and second endovascular stent-grafts (20, 22), which include respective first and second stent bodies (32, 108), and respective first and second fluid flow guides (102, 109). The first stent-graft (20) is shaped to define an interface portion (103) having a distal interface end (34) that meets a proximal end (36) of the first stent body (32) at a peripheral juncture (104). The second stent-graft (22) defines an interface aperture (110), within which part of the interface portion (103) is positionable. The interface portion (103) comprises engagement support members (105) disposed around a periphery thereof, which are configured to transition from an initial state to (b) a sealing state, thereby sealingly coupling the first stent-graft (20) to the second stent-graft (22) when the part of the interface portion (103) is positioned within the interface aperture (110). Other embodiments are also described.