Moulded from Grilamide TR90, a thermoplastic polyamide. Dirty Dog TR90 sunglass frames are lightweight, extremely flexible yet super strong with 100% memory allowing the frames to bounce back to their original shape. Put through the harshest testing conditions, Dirty Dog eyewear has proven TR90 will keep its properties in extreme temperature including low and high temperatures, as well as extremely humid or dry conditions. This makes them the perfect choice for any situation and gives the wearer a guarantee that they will stand up to the job. TR90 has demonstrated no risk of allergy and is FDA and CE approved.