TB2 is a high-squareness MnZn power ferrite with an initial permeability (μi) of 1500, a saturation flux density (Bs) of 580 mT at 25 °C (460 mT at 100 °C) and a Curie temperature above 220 °C. Its characteristic feature is a remanence (Br) of 420 mT at 25 °C (330 mT at 100 °C), a squareness ratio Br/Bs of about 0.72 and a near-rectangular hysteresis loop: the core switches distinctly between its two saturated states and retains most of its flux after excitation is removed, which is the operating principle of magnetic amplifiers and saturable reactors. The corresponding penalty is a coercivity (Hc) of 30 A/m at 25 °C (25 A/m at 100 °C) and higher loss (25 kHz / 200 mT: 310 → 430 kW/m³; 100 kHz / 100 mT: 440 → 760 kW/m³). Typical applications are mag-amp regulators, saturable reactors, ballast trigger cores and switching chokes. Among the three conventional low-frequency grades TB2 is the only one selected for squareness: low-loss transformer and choke duty is served by T2/T2M, and higher Bs and DC-bias tolerance by the high-Bs special grade TM82. The grade is intended for circuits requiring switching-type magnetisation and is not recommended for linear transformers.