There is a tonneau or covering device for covering an open storage portion of a vehicle. The tonneau includes a cover, a cord, and/or a plurality of couplers, such as but not limited to hooks. The cord is disposed circumferentially about the cover and coupled thereto through sheathes. There are double-hook couplers including a first hook removably coupleable to a cord and a second hook coupled to the first hook and removably coupleable to the vehicle. The second hook may include a U-shaped member. The first hook may include a tapering hook opening. The first hook may include a flexible hook opening.
