1) optical glass (borosilicate) material 2)above 94% light transmittance 3) high temperature resistance 4) clear Material: optical glass (Borosilicate,K9 and so on) Up to 96% transmittance size and weight Diameter :127mm weight : 220 g/piecePacking : 2 pcs /bubble bag packing Processing: by design, molding, grinding, polishing, inspection, testing and so on Inside quality: clear and transparent, ...