Bring desktop-class PCIe expansion to Thunderbolt systems without redesigning the workstation. OWC Mercury Helios 5S gives laptops, Macs, and PCs a direct path to PCIe cards through Thunderbolt 3, Thunderbolt 4, or Thunderbolt 5, making it easier to add specialized capture, networking, storage, or audio hardware where internal slots are limited. Built around Thunderbolt 5, the Helios 5S delivers up to 80 Gb/s of host connectivity and includes dual Thunderbolt ports for flexible daisy chaining. It also provides 85 W laptop charging, reducing cable clutter while keeping mobile systems powered during long sessions. The enclosure is designed for PCIe-based expansion rather than graphics acceleration, making it a practical fit for professionals who need reliable access to add-in cards in a compact footprint. For teams that value compatibility and control, this enclosure offers a clean way to extend existing systems instead of replacing them. It is a strong choice when the card matters more than the chassis, and when uptime, desk space, and connection quality all carry real cost.