Following on the heels of mLogic’s mLink, OWC’s Mercury Helios PCIe Thunderbolt Expansion Chassis ($349) has arrived as a less expensive alternative in a slightly less attractive package. They both achieve the same end: any Thunderbolt-equipped Mac can use a half-length PCIe card that was formerly compatible only with the Mac Pro. PCIe cards can be used for everything from flash storage to video capture, enabling Mac Minis and iMacs to serve as professional-class workstations.
There are a few key differences between the two companies’ enclosures. We prefer the industrial design of mLink, but Mercury Helios is $50 less expensive. The latter doesn’t have a power button; instead, it turns on and off automatically with your Mac. They both have a pair of Thunderbolt ports on the back, allowing you to daisy-chain multiple devices. It’s nice to know there are a pair of good options on the market for those who need expandability accessories.