It is a 0.3 Ohm 3W Surface Mount Sense Resistor. This is, in general, a low-value, high-power resistor. Ideal for all types of current sensing and pulse applications including switching and linear power supplies, instruments, power
amplifiers, shunts, power inverters, and battery management.
3 x 0.3 Ohm 3W Surface Mount Sense Resistor.