The Capacity Gauge (inner LED) consists of six sections which illuminate in a clockwise direction to indicate space used on the drive. Each section represents approximately 17 percent of disk space. The power/activity and capacity gauge LEDs are two concentric rings on the front panel of the drive. The outer ring is the power/activity LED and the inner ring is the capacity gauge LED. Device Type: Hard drive array Total Array Capacity: 10 TB Interface: USB 3.0, Thunderbolt 2 Installed Devices / Modules Qty: 2 (installed) / 2 (max) Localization: Canada, Latin America, United States Storage Controller: RAID RAID 0, 1, JBOD Hard Drive: 2 x 5 TB HDD - hot-swap - Apple Time Machine compatible, HFS+ formatted, toolless OS Required: Microsoft Windows 7 or later, Apple MacOS X 10.7 or later Power: AC 120/230 V - 50/60 Hz Dimensions (WxDxH): 4.3 in x 8.5 in x 5.8 in Weight: 7.76 lbs Manufacturer Warranty: 3 years warranty Device Type: Hard drive array Enclosure Color: Silver/black Localization: Canada, Latin America, United States Installed Devices / Modules Qty: 2 Supported Devices / Modules Qty: 2 Total Array Capacity: 10 TB HDD Array External Interface: USB 3.0, Thunderbolt 2 Type: Xeon Type: RAID Cache / Buffer Size (Max): 4 GB RAID Level: RAID 0, RAID 1, JBOD Type: HDD - hot-swap Capacity: 2 x 5 TB Spindle Speed: 7200 rpm Features: Apple Time Machine compatible, HFS+ formatted, toolless Expansion Bays: 2 (total) / 0 (free) x hot-swap Interfaces: 2 x USB 3.0 - 9 pin USB Type A 1 x USB 3.0 - 10 pin Micro-USB Type B 2 x Thunderbolt 2 OS Required: Microsoft Windows 7 or later, Apple MacOS X 10.7 or later Features: Metal housing Cables Included: 1 x USB 3.0 cable 1 x Thunderbolt cable - 3.3 ft Software Included: WD Drive Utilities Compliant Standards: RoHS 2002/95/EC Power Device: External power adapter Voltage Required: AC 120/230 V - 50/60 Hz Width: 4.3 in Depth: 8.5 in Height: 5.8 in Weight: 7.76 lbs Service & Support: 3 years warranty Service & Support Details: Limited warranty - 3 years Min Operating Temperature: 32 °F Max Operating Temperature: 95 °F