Those are my DIY mitts. Tested at -36C, 5hrs. They are an improved version of the Choko mitts. I don't know what their temperature limits is. But i have no doubt they are good at -40F.
The wool liners are Ortovox wool liners (pretty much like dachstein)



My gloves are also DIY from Choko. They have been tested at 0F which is their limit. Comfort is better at 5F or 10F. Without those modifications they are good up to 30F.