The present disclosure describes an occlusion device and methods of delivering the occlusion device. The occlusion device can include an expandable structure configured to move between an unexpanded configuration and an expanded configuration. The expandable structure can be configured to have an expansion ratio of at least about 5:1. Further, the occlusion device can be configured to prevent substantially all fluid from flowing past the occlusion device when the occlusion device is in the expanded configuration in the vessel.
