text: Entry-level ferric formulations are made of pure, unmodified, coarse-grained ferric oxide. Relatively large (up to  in length), irregularly-shaped oxide particles have protruding branches or dendrites; these irregularities prevent tight packing of particles, reducing iron content of the magnetic layer and, consequently, its remanence (13001400G) and maximum output level. The squareness ratio is low, around 0.75, resulting in early but smooth onset of distortion. These tapes, historically labeled and sold as low noise, have high levels of hiss and relatively low sensitivity; their optimal bias level is 1–2dB lower than that of the IEC reference tape.
  This group also includes most of the so-called Type 0 cassettes — a mixed bag of ferric tapes that do not meet the IEC standard or the original Philips specification. Historically, informal Type 0 denoted early cassettes loaded with tape designed for reel-to-reel recorders. In the 1980s, many otherwise decent and usable basic tapes were effectively demoted to Type 0 status when equipment manufacturers began aligning their decks for use with premium ferricobalts (the latter having much higher sensitivity and bias). In the 21st century, Type 0 denotes all sorts of low-quality, counterfeit or otherwise unusable cassettes. They require unusually low bias, and even then only a few of them perform on par with quality Type I tapes. A Type 0 tape, if it is usable at all, is incompatible with Dolby noise reduction: with the Dolby decoder engaged, the tape sounds dull, resulting from its poor sensitivity causing severe Dolby mistracking.