A self-tightening lamp formed from spring steel band material which exerts clamping forces by the inherent springiness of the band material. To minimize outwardly projecting parts with their injury danger and to obtain an inner clamping surface substantially devoid of any gaps or steps, the end of the outer band end portion is provided with an elongated slot adapted to receive the tongue-like overlapped inner band end portion. Temporary locking of the clamp is realized by a detent member in the tongue-like inner band end portion adapted to be lockingly engaged by a locking surface in the outer band portion. The elongated slot is thereby of such width as to accommodate the tongue-like inner band portion whereby the detent member is located in the elongated slot when the clamp is in its clamping position.