Promise Brand Thunderbolt Computer Storage Devices
Primise was the very first manufacturer to even offer a ThunderBolt storage device when Intel and Apple first introduced the interface. Sadly they deliver high-end enterprise solutions with multi-drive hard disk based RAID arrays that begin at 1 thousand dollars and up. It wasn't till nearly a year later that LaCie delivered the first solid-state ThunderBolt RAID device in it's 'Little Big Disk' series. And it too, at $799, was far too expensive for most Mac users.
Promise Single-Drive ThunderBolt Backup Drives
As a company Promise really isn't into the consumer hardware space at all. They're strictly a high-end, high-performance company catering to the most demanding data storage and transfer markets who are far more likely to use rack-mount arrays for businesses than anything for the consumer space.
Promise Multi-Drive Desktop ThunderBolt RAID Backup Drives
The Pegasus line starts with a quad drive hardware RAID enclosure using 3.5" HDD drives and goes up from there. They've been on the leading-edge since ThunderBolt's inception: First with 10Gbps original ThunderBolt, then updated quickly to 20Gbps ThunderBolt 2. They're now offering 40Gbps Type-C ThunderBolt 3 RAID arrays for the most demanding environments.