Patent ID: 6896461

Claim:
A spring fastener comprising: a double layered head portion having an upper side, and a lower side, the upper side having an engageable hole on which a threaded expanding member can engage and pass through, the threaded expanding member having a pitch, the upper side and the lower side being separated by head-side separators, which prevent the two sides of the head to come close together or in touch with each other, when adequately high torques are applied by the threaded expanding member; and a body portion extending from the lower side of the head portion, the body portion comprising two legs opposite to each other, each leg comprising an open neck, a respective substantially flat origin section originating from the head, and leaning at a lower point toward a respective substantially flat front portion away from the head, and wherein the respective origin sections of the legs are separated from each other by a first distance which is larger in the vicinity of the head than a second distance separating the respective front portions of said legs, the legs also comprising a contact region, on which contact region the expanding member exerts force causing said legs to expand when said expanding member is inserted into the fastener through the engageable hole.