The Shield is compatible with any Arduino board using UNO-R3 Shield headers, running at either 3.3V or 5V levels, by using the IOREF pin to select the EasyVR operating voltage.
It is also backward compatible with earlier Arduino boards that don’t have the IOREF pin, which are using 5V I/O levels by default.
If your board does not have the IOREF pin but it is running at 3.3V, you can still operate the EasyVR Shield 3 correctly if you manually connect pins IOREF and 3V3 together, for example with a jumper wire.
The board comes with separate Arduino stackable headers for the Shield interface. The EasyVR 3 module is also provided separately.
Learn more about it on the EasyVR Shield 3 product page.