Product review (3 stars): This is a very expensive piece of glass.
Seems a bit fragile, no frame around the edges.  We have had two break from impacts of unknown origin.  Possibly a can or a pot striking at the wrong point of impact. For our family, a four hundred dollar piece of glass is way too expensive to replace.  It may be wise to purchase a cooktop with a frame around the glass, rather than replace the broken glass multiple times.