1) optical glass (borosilicate) material 2) above 94% light transmittance 3) ... temperature resistance 4)clear solar concentrator glass lens(GT-D22-10-1)1)material: optical glass(borosilicate),K9,BK7,B2702) light transmittance: 95 ... ,optical instrument,astronomical instrument. solar concentrator glass lens(GT-D22-10-1)