Nathair Mitts are a soft and squishy pair of mitts with a centered cable going down the back of the hand. They feature a regular style thumb gusset, with mirrored increases on either side of the thumb, making a nice little area for your thumb to fit cozily.
The official first pattern in my Smart Thumb series. This is the basic thumb gusset, as you find in many patterns.
The fingers must be educated, the thumb is born knowing. ~Marc Chagall