Western Digital has expanded its line of Mac-compatible external hard drives. The company is adding a USB 2.0 model to its existing WD Dual-option product family, which features software that simplifies and automates data back up; and is introducing the WD Essential external drive family, which provides “the necessary storage functions and maximum value.” Both WD Dual-option USB 2.0 and WD Essential drives feature a front-mounted power button, USB 2.0 interface, 7200 RPM spin speed, and come in capacities of 80, 120, 160, 200 and 250 GB.