Thunderbolt (and lightning) may have been very, very frightening to Freddie Mercury, but Apple fans have been pining away for stuff to use with the Thunderbolt port on their Macs. Western Digital’s My Book VelociRaptor Duo puts the waiting to an end, literally. This ultra-fast desktop RAID offers blistering speed, but it comes at a cost.

If you’ve used one of WD’s My Book drives before, the VelociRaptor Duo will look familiar. The vaguely book-shaped case contains a pair of 1TB drives. But these are WD’s 10,000-rpm VelociRaptor units — they’re much faster than the stock drive in your Mac, and using them as a single striped RAID volume gooses the speed even more.

The VelociRaptor Duo is simple to set up. Plug the device to AC power, connect it to your Mac via Thunderbolt, and you’re good to go. Thankfully, the Thunderbolt cable is included, saving you about 50 bucks over other Thunderbolt peripherals that arrive sans cable. Out of the box, it’s configured as RAID 0. Your data is written across both drive mechanisms, which gives you maximum read and write speeds, and the full 2TB capacity. The included software can reformat it to RAID 1, writing a copy of your data to each of the two drives. That increases the safety of your data, but reduces the speed and capacity (to 1TB). And frankly, if you’re using this device for backup, you’re doing it wrong. What you’re paying for is speed, and there are plenty of cheaper options for redundant backups.

At well over 800 bucks for 2TB, the VelociRaptor Duo isn’t made for extensive collections of cat GIFs and episodes of The Walking Dead. But if you’re working with pro-level HD video, the speed will come in handy. Throughout our tests, we got write speeds in excess of 350MBps and read speeds approaching 380MBps, using a 2012 2.9GHz Core i7 MacBook Pro. Of course, RAID 0 also makes it twice as likely that your volume will fail—if one drive goes down, your data will be lost. But given the reliability and robustness of WD’s VelociRaptor mechanisms, that’s not really much to be afraid of. Plus, if you’re using this kind of prosumer gear, you should have a separate backup system in place anyway.

The bottom line. The VelociRaptor Duo takes the some of the fright out of ultra-fast RAID storage. Video production folks will find the price worthwhile, but everybody else is better off looking at less-expensive USB alternatives.