HamiltonBuhl Flex-Phones are nearly indestructible, made from a single piece of EVA foam. EVA foam is safe, non-toxic, BPA-free, soft and an extremely flexible material. Flex-Phonesare certified for all major USA and international child safety testing s tankards. We are extremely proud that they have been awarded the Scholastic Teacher's Pick as "The Best of 2015". Recommended for children ages 3 and up, Flex-Phones are packaged with a snap-on extension band for smaller children just snap on the extens ion band for a snugger fit. Most importantly, the extremely clear sound quality will never exceed 85 decibels, ensuring young developing ears are protected. Drivers: 30 mm. 4' cord length. Impedance: 32. Warranty: 1 Year. Sensitivity: 82dB plus or minus3dB. 3. 5mm stereo plug. Frequency Response: 20Hz - 20KHz. The HamiltonBuhl Red Flex-Phones are constructed with a single piece of indestructible EVA foam that is soft, non-toxic, BPA-free, and flexible making it safe for used by children aged three years and above.