This chunk of glass was used in the glass box scene with Hoffman (Costas Mandylor) as he opened the glass box in SAW 6! The glass chunk is made of silicone...it looks just like real "jagged" glass! Each chunk of glass was specially created by the SAW VI props team specifically for this very famous scene in SAW 6! Sorry for the pic its not the best but this looks very cool, and real in person. See pic below of this scene in the film.
