This is quite old. It's glass with stained glass fused to a layer of clear glass. This thick glass can only be made with a large kiln. Thickness: Approximately 7-8mm 305mm x 238mm The edges seem to have been smoothed. I'm selling it because I don't need it. Rather than being a stained glass material, due to its considerable thickness, I think it's suitable for interior partitions or exterior use as a building material. Rare material. Free shipping. #ResidentialBuildingMaterials #GlassBlock #StainedGlass #Materials #Bullseye