Astria Blackstone 42 inch Black Standard Bi-Fold Glass Door BDB42Astria Blackstone 42 inch Black Standard Bi Fold Glass Door BDB42 Product Details What is the function of the Astria Blackstone 42 inch Black Standard Bi Fold Glass Door, and how does it improve the safety and aesthetic appeal of a wood burning fireplace? The Astria Blackstone 42 inch Black Standard Bi Fold Glass Door serves both safety and aesthetic functions for wood burning fireplaces. Its primary role is to provide a protective barrier between the