Product review (5 stars): This IS the spring you're looking for.
PERFECTION!

I've got a Samsung RF261BEAEBC French door refrigerator that had its mullion spring fail. If you're here, you're most likely wondering if this spring will fix that center bar (mullion) on your refrigerator door so it springs into place when you open it.

If you look in the pictures I've included, you'll see the mullion has a few places where you can insert a screw driver to pry its cover off and access the spring. Be careful as there is a small rubber seal at the top that's easy to lose and two pieces of insulating styrofoam that will also fall out of the mullion.

Also in the pictures, you'll see the old spring and the way it broke. I'm not sure if it's due to low quality metal being used for the spring or the repetitive use stress that caused it's failure but this replacement spring works well. $9 is a lot cheaper than the $75 it costs to replace the entire mullion assembly.

Hopefully all of this info and the pictures help you replace your spring and fix your fridge too :)