A speaker includes a base having a groove, a tube received in the groove, a magnet disposed in the tube, a first ring-shaped body and a washer mounted, from top to bottom, on an outer side of the tube sequentially, and a second ring-shaped body connected to an edge of the first ring-shaped body and installed around a wall surface of a rim of the groove. The second ring-shaped body has an inner ring-shaped plate, an outer ring-shaped plate, and a connection segment connected between the inner ring-shaped plate and the outer ring-shaped plate. Therefore, a low-frequency effect thus generated is greatly improved.