This hard drive caches frequently random-accessed parts of files. What this does is allow one to have the capacity of a hard drive, yet (after it's learned which data actually benefits from flash) have the low latency of flash-based storage. It's about five times slower in terms of sequential read performance than an SSD, but that's not what makes a pc fast. It's the latency that makes the biggest difference. In many ways, it's similar to the technology in Intel's Smart Response Technology, or Apple's Fusion Drive (which is probably just rebranded SRT), but it's on the hard drive itself and not on the motherboard. This then is a set-and-forget solution for tiered storage, ideal for platforms without SRT support, for people who prefer to spend money on other things than SSD's or simply don't want to bother with having a boot drive and a separate storage drive. This is what has saved mechanical storage from obsolescence.