DEV-11018 Datasheet PDF - SparkFun Electronics

Overview: 
   The RFM22 shield is an Arduino-compatible shield which provides a means to communicate with the HOPERF RFM22 radio transceiver module. What does THAT mean? It means you can use the RFM22 shield to add wireless communications to your Arduino projects.
   This tutorial will give you the information you need to assemble your shield and start using it.