Originally Posted by
OneIsAllYouNeed
SRAM makes one. It's about $38 on Jenson. Be aware that the "USAmade" one is intended for 1X drivetrains only, while the SRAM one is for 2X. The Vuelta and Sugino offerings work (but not as well) for 1X, 2X, or 3X drivetrains.
The one I ordered from USAMade states:
"Designed for outer ring position double chainring cranks"
I hope that means what I think it means.