the first commercial use of cr-39 monomer was to help create glass-reinforced plastic fuel tanks for the b-17 bomber aircraft in world war ii, reducing weight and increasing range of the bomber. after the war, the armorlite lens company in california is credited with manufacturing the first cr-39 eyeglass lenses in 1947. cr-39 plastic has an index of refraction of 1.498 and an abbe number of 58. cr-39 is now a trade-marked product of ppg industries.