USF 1206 Surface-Mount Fuses Schurter USF 1206 Surface-Mount Fuses are UL Super-Quick-Acting FF fuses with fast interruption properties. These fuses offer low melting I2t-values and operate at 32VAC to 125VAC/63VDC to 125VDC rated voltage ranges. The USF 1206 fuses are impermeable to potting compound and incorporate 50A breaking capacity. Schurter USF 1206 Surface-Mount Fuses are best suited for secondary protection DC and AC, circuits without inrush, and semiconductor protection.