CR 39 1.49HMC optical lens, high grade finish EMI Finished and semi-finsihed attractive price... 1) ND: 1.499 2) Diameter: 70mm / 65mm Features:1) ND: 1.4992) Diameter: 70mm / 65mm3) Curvature: 50B, 200B, 400B, 600B, 700B, 800B, 900B, 1000B4) Concave base: 500B5) Central thickness: 11mm - 13mmgood quality and A-grade . CR 39 1.49HMC optical lens