An endovascular stent graft delivery device (1) has a portion (2) to remain outside a patient in use and a proximal portion (3) to be introduced into a patient. The proximal portion (3) has a dilator (12) at the proximal end and a length extending module (20) that is fastened to the dilator (12) and extends proximally. The length extending module (20) has a proximal end which in use extends out of the patient. The dilator (12) has a dilator marker (12d) and the length extending module has a first marker (25a) and second marker (25b) at the distal and proximal ends of the length extending module (20). The first marker (25a) and the second marker (25b) are at the same relative circumferential position on the length extending module (20) so that the rotational position of the elongate body of the delivery device (1) within the patient can be determined.
