| Trademarked from the Pittsburgh Plate Company (PPG) in the 1940's, CR-39's complete name is Columbia Resin #39. Possessing an index refraction of 1.50, CR-39 is the most widely used lens type on the market. With the increase in technology, many consumers have begun to shift towards other thinner and lighter materials. However, CR-39 remains the popular choice of many due to its affordable pricing and availability. |