The CR1210JR390P05R is a surface mount, 0.39Ohm ±5% resistor from Ever Ohms rated at 1/2W, 1210 in size, and compliant with RoHS regulations. This low-resistance, current sense resistor is used to measure electrical current or to control element temperatures in many types of electronics, including amplifiers, LED drivers, power controllers, and more. It's designed to dissipate low levels of power while allowing for a high degree of accuracy and low thermal output, making it ideal for breadboards and tight electronic circuit applications.