hray

I was straightening up my sewing table drawers and came across this foot. I cannot figure out what it is. On the plastic is the letter D. My machine is a Brother VQ3000.

The red knob moves the black shank a bit left/right. In front of the red knob, there is a double-ended arrow with a +/- next to it.

The left toe is a bit higher than the right toe.

Any ideas? It’s driving me nuts. Thanks!