HPE Altoline 6900
Based on the earliest date in data sheet, March 2016
In addition to four SFP+ ports for uplinks, the switch has 20 Gb/s stacking ports presented as QSFP+. Note that software vendor Cumulus has no use for stacking ports since they are focused on the data center and top-of-rack switches. Stacking ports are useful when the task is to build a large array of ports for an access arrangement in a cable closet. That is not Cumulus' market.
There is a data sheet.
The Altoline 6900 has a switch element integrated with a dual core ARM processor. We're guessing: higher integration yields lower manufacturing cost. It also saves on power.