SONY CDIT74/50 74-Minute High Bias Type II Blank Audio Cassette (Case of 50) Sony's High-Bias Type II Audio Cassettes. 74 Minute of Recording with Slim Case Storage. Ideal for recording CDs, prerecorded cassettes and other digital sources. Formulated with more densely packed particles to provide higher output and wider dynamic range than HF normal bias tapes. Sold as a wholesale master case of fifty (50) cassette tapes.