Purchased new from QNAP in September 2016 for £480 + shipping.

Performs well as 2 independent 10GbE SFP+ channels, but can be configured (using QNAP NAS software, included with most QNAP NAS models) in trunked / bonded mode to give 20GbE bandwidth, either connected via a switch, or directly to another SFP+ device (such as NAS, PC or Mac Pro).

Comprehensive configuration for:  Load Balancing, Failover, Port Trunking, Active Backup, JBOD, 802.3ad dynamic, IPV4, IPV6, VLAN 802.1q, Balance-xor, Balance-rr, Balance-tlb and Balance-alb, and Broadcast modes of operation.

This item is only intended for installation in a QNAP NAS device, such as TVSx82T, TVSx82, TVS871T, TVS871, or a QNAP device with spare PCIE slot.

I had 2 of these installed in QNAP TS563 and TVS1282T, networked to a SFP+ switch, and a Mac Pro 5,1.

I also have a number of SFP+ cables for sale - see my other eBay listings.

Please feel free to ask any questions.