The overlays have barcodes that are read by the VocaFlex. When a different overlay is placed on the device, the VocaFlex automatically changes the keyboard configuration and vocabulary to match the overlay.
The different models have from 30 minutes to 2 hours of speech. They are available with either single key activation or sequencing.
VocaFlex has an excellent voice output and is powered by rechargeable lithium–Ion batteries.