True blast plus sound system – Alco fa - O scale. Add realistic sounds to older Williams locomotives with this true blast plus sound system. Features include: true blast plus 16-bit polyphonic sound including Prime mover, horn, and bell, Alco 244 Prime mover with Waco E2 horn and Alco bell, installation instructions included, speaker with sound enhancer dimensions: D = 2", H = 1 1/8", designed for AC operation 0-18 Volts.