A 500GB hard drive that’s only 5mm thick? About as easy to believe as me telling you there are unicorns grazing on your front lawn, right? Well, Western Digital announced today that they’ve started working with that very creature (the hard drive, not the unicorn). The tiny drives use a small amount of solid-state storage alongside the traditional spinning hard drive that will provide the speed of a solid-state drive without the hefty price.

The hard drive in a standard laptop is around 9.5mm thick (pictured above), although the higher the capacity of the drive, the thicker the drive. The thinnest ones on the market right now are around 7mm (in computers such as the Acer Timeline M5). Western Digital is taking thin and powerful to the next level with these advanced ultrathin hard drives, presumably for future Ultrabooks but at that size could fit elsewhere too. Although hybrid tech is a big reason behind the speed an thinness of the drive, it helps that as technology advances, the hold capacities of drives are getting larger while physically drives are taking up smaller and smaller amounts of space.

Unfortunately we have no information about the quality or speed of the MLC NAND flash storage that’s going to be used in these thin drives. It’s estimated to be similar to the 20GB to 32GB solid states that are available in current Ultrabooks. Also, it’s still going to be a wait before you can claim one of these lovely skinny drives for yourself — no release date has been announced yet and an estimate is that these hybrids will be showing up in Ultrabooks some time next year.

Maybe you should check your lawn for that unicorn, after all.

[via ArsTechnica]