HamiltonBuhl Flex-Phones HamiltonBuhl Flex-Phones are virtually indestructible, made from a single piece of EVA foam. EVA foam is safe, non-toxic, BPA-free, soft and an extremely flexible material. Flex-Phones are certified for all major USA and international child safety testing standards. Recommended for children ages 3 and up, Flex-Phones deliver excellent, clear sound quality that will never exceed 85 decibels, ensuring young developing ears are protected. Flex-Phones include a snap-on extension band for smaller children – just snap on the extension band for a more snug fit. Flex-Phone Specs Drivers 30 mm Impedance 32Ω Frequency Response 20Hz - 20KHz Sensitivity 85dB ±3dB Cord 4' Dura-Cord - chew-resistant, PVC-jacketed, braided nylon Plug 3.5mm TRS stereo plug