I bought the glass from Home Depot or Lowes, can't remember which one or what the thickness was.
But it's pretty thin, I think maybe 1/8".
I wanted thicker but the only place I could find it was at a glass shop like Lee & Cates and they're not open Saturday so it was a pain to get it from there.
If I had to do it over again I would hold out for the thicker stuff since I'm always worried about bumping a baffle and breaking it.
As for the silicone, I used GE Silicon (I or II) 100% silicone from HD/Lowe's.
Make sure you get the Window and Door kind, not the bathroom & kitchen one.