This Western Mountaineering Megalite bag has a double layer on the top and a single layer on the bottom. It’s rated to 30 deg F. Aaron has used it in 5 deg F temperatures. It was a little chilly but it kept him safe.
If you sleep a little bit colder, I’d suggest the Ultralight (20 deg F) or Versalite (10 deg F) bags. These both have a double layer on the bottom for added warmth.