Using a video, audio, storage, network, or even gaming PCIe card with a Mac Pro or PC desktop is a simple matter of inserting your card into an open slot. But what do you do if you have a laptop or even a space-confined desktop like an iMac or Mac mini that doesn't contain a PCIe slot, The OWC Mercury Helios 3S is an easy to use yet powerful expansion solution that adds an external PCIe slot to your Thunderbolt 3 equipped computer. Now you can maximize your existing PCIe card investment or expand it while enjoying the flexibility of adding professional-class video production, transcoding, audio processing, data storage, and high-speed network connectivity to your machine. Instead of buying one or more function-dedicated Thunderbolt interface devices, you can use Mercury Helios 3S like a dock for multiple PCIe cards. Capture incredibly high-quality audio with a PCIe audio card and then retask Helios 3S with a PCIe SSD card to edit and archive tracks. You can swap cards in minutes, adding a new level of flexibility to your workflow. Mercury Helios 3S supports a wide variety of half-length, full-height, single or double-width pro-level PCIe cards from leading brands like AJA, Apogee, ATTO, Avid Pro Tools, Blackmagic Design, CalDigit, HighPoint, Intel, Solid State Logic, Universal Audio, and OWC: Video capture Digital audio Solid State Drive (SSD) 40GbE/10GbE network adapters SAS controllers Firewire, USB, or eSATA host adapters.