Bivy?

[Mjm316]

I'm looking for a bivy for a semi rectangular feathered friends bag. Any thoughts or options. FF suggested a black diamond bivy. Just looking for options. I know they will be slim for the semi rectangular bag but that's what I prefer

 

[vegas hunter]

I use a Katabatic Bristlecone bivy with my FF Puffin. Fits with room to spare.