ForceFlex® FF1 technology incorporates a patented, multi-injection molding of the lens with a flexible Thermo Plastic Urethane (TPU) frame. Due to this construction, it can achieve a military ballistic level impact resistance at over 1000 feet per second. The TPU material allows the frame to flex and fit individual faces from large to small. All ForceFlex® FF1 safety glasses meet military MIL-PRF-31013 clause 188.8.131.52 for high velocity impact protection and exceed ANSI Z87+. This achievement benefits consumers by providing unparalleled levels of protection. The dual material temples combine Thermo Plastic Rubber (TPR) for comfort and polycarbonate for durability. MCR Safety's Forceflex® FF1 eyewear is engineered to provide the highest level of innovation for consumers that demand the very best in safety. These high quality safety glasses have a lifetime frame warranty and are engineered to provide the highest level of innovation. Choose the best safety glasses, choose MCR Safety!