In recent years, bi-fold fireplace doors have become the most popular
variety.
The term "Bi-Fold" refers to doors which each fold in the
middle during opening the doors. This is like the operation of some
closet doors. This means that there are actually
four pieces of glass. The advantage of bifold doors is that they
don't stick as far out into the room when they're open.This style has a metal frame that surrounds each pair of the glass panels.
JDoor's
Fireplace Door Selector Page is at:
http://mb-soft.com/juca/info/doors/firedoor.html