Cassette enclosed in oversized clear plastic book. From the packaging: "Headphones Required Digital Recording." "Clear Coherence provides a brain hemisphere synchronization experience in the Theta (4-7 Hertz) and Beta (14-30 Hertz) brain wave range. This provides an alert creative mental state with a relaxed physical posture. The relaxation response is the shortest path to better learning and more efficient mental power. Clear Coherence induces a calm but alert and a relaxed but focused state of experience. Side B inverts the frequencies presented on side A. Set tape player to auto-reverse for extended sessions of contemplation."