An occlusion system can include an expandable implant that can be delivered to a bodily lumen. The implant can be carried on an engagement section of a catheter used in the system. The implant can be assembled onto the catheter by coupling a cover member of the implant with a support member of the implant. When assembled, the system can be advantageously configured to have a low delivery profile to facilitate delivery through catheters having a size of less than 7 Fr, and in some cases, less than 6 Fr.