Nu-Vois III High quality voice with full digital control of tone and volume. Dual On/Off Control buttons can be set for desired pitch and volume without disassembly of the device.	Nu-Vois II High quality voice with full digital control of tone and volume. Outer case is made from durable polycarbonate, a high-impact resistance and durable material.	Nu-Vois I High quality voice with full control of tone and volume. Outer case is made from durable poly-carbonate, a high-impact resistance and durable material.