The vision TFA aerobar is one piece, and has the base bar detach from the stem and flip up or down. At least it does in the diagram. I don't know if the is actually for sale yet, or its just out of stock.
METRON TFA aerobar | VISION (visiontechusa.com)

And there was a profile design one, Svet R I think, it would go high or low as opposed to flat.

I have a gen 2 speed concept, I really wish my bullhorns could go up like that.

Thanks, that is what I am looking for, but I have a BMC TM01 with a unique stem... so I need something with a 31.8mm bar... I'll look at the PD SVET

EDIT... these Vision bars fit the bill... but they include extensions (which I don't need)... https://shop.visiontechusa.com/...trimax-carbon-si-013

Profile Design Wing20C
The 20 refers to the height difference in the grips when you flip them