... Vision optical lens factory(CE,FDA) 1)Refractive index:1.56 2)Diametre:70/72mm 3)UC,HC,HMC 1.56 ... HMC Single Vision optical lens ... factory(CE,FDA) Refractive index:1.56Material:NK-55Abbe ... photochromic lens(Grey, Brown),with index of 1.499, 1.56, 1.60, 1.67, both in finished and semi-finished, ...