There is disclosed herein a tube of material (1) having a seam (12) extending between a proximal end and a distal end, two edges (10a, 10b) of the material meeting and at least partially overlapping along the seam (12) and being sewn together at the seam by stitches (21, 22, 24) of relatively flexible thread (20), the thread of one or more of the stitches (22, 24) passing from a first side (12a) of the overlapped edges (10a, 10b) of material, through both layers of overlapped material, crossing a relatively rigid member (30) which is disposed on a second, opposite side (12b) of the overlapped edges of material, and passing back to the first side (12a). There is further disclosed an implant delivery catheter (40) incorporating the tube of material (1), and associated methods for its manufacture.