The holes are part of the unit’s revolutionary new cooling system engineered to ensure overheating and data loss does not occur. Like its peers, the XD4 offers eSATA I, eSATA II, and USB 2.0(1) interfaces for easy connectivity with a PC. At its slowest (USB), it transfers at 480Mbps, but can easily be hooked up by eSATA II to render speeds up to 3Gbps. Most unique about the LG XD1 is its flexible compatibility, as it works with all major Windows operating systems AND Mac OS 10. Also note that the XD4 features a convenient one-touch backup button for quickly and safely backing up computer data in an emergency.