The Unified Zebra RFID SDK for Android provides a powerful set of APIs to take full advantage of the RFD40, RFD90, MC3300xR, RFD2000, MC3300R and RFD8500 performance, functionality and versatility. The SDK also contains the Zebra RFID Mobile API application that can be used as reference to develop new applications or to port existing applications to take advantage of the reader features.
Source: Zebra RFID Reader SDK for Android Support & Downloads | Zebra