Casio PX870BN Privia 88-Key Digital Piano w/ Cabinet Stand & Pedals (Walnut)PIANO PURITY! The PX 870's award winning AiR Sound Source includes a new four layer stereo grand piano which comes alive with realistic damper resonance, simulating the entire body of the instrument, not just the strings. The piano also includes key action sounds, key off simulation, adjustable hammer response, and a lid simulator with four positions. The PX 870 also includes string resonance, which exposes the sympathetic harmonic relationships