Thanks Jim.it provides the seal between the two doors, when they are closed. Just about every French door frig uses that method.
Thanks KMacMake sure when you open the left door, that flapper is FULLY out (towards the front), otherwise you will experience poor cooling in the fridge part. Just use your hand to pull it forward. It took me 2 years to "accidentally" trip over a video while troubleshooting my fridge issues, showing exactly what to do.
Good luck and have fun!
//KMac