DL4 is a NiZn ferrite with an initial permeability (μi) of approx. 600, a saturation flux density (Bs) of approx. 350 mT at 25 °C (265 mT at 100 °C) and a Curie temperature above 200 °C. The higher permeability raises the inductance per turn — most directly in toroids and other closed-magnetic-circuit precision transformers and filters — while the low coercivity (Hc approx. 32 A/m) keeps hysteresis loss and signal distortion low; with a relative loss factor of only 12×10⁻⁶ at 0.1 MHz under low flux it suits precision signal paths, though the loss rises faster with frequency (80×10⁻⁶ at 1.5 MHz), placing its useful band somewhat lower than DL3's. Excellent thermal-shock resistance and solderability withstand reflow temperature swings. Typical uses are high-accuracy wideband transformers, sensing coils, EMI filters and impedance-tuning coils — especially sensitivity-critical SMD designs — as well as low-current HF power inductors in mixed signal/power modules. Within the DL family, DL4 is the sensitivity-oriented grade: its nominal permeability is roughly 70 % above DL3's (μi approx. 350) over a slightly narrower band; choose DL5/DL6 for higher flux density and temperature capability.