A wireless initiation device comprises a power source, a processing module, a first housing and an initiation unit. The processing module processes wireless electromagnetic communications signals received by an electromagnetic receiver system associated with the processing module. The wireless electromagnetic communications signals includes a wireless electromagnetic communications signal representative of a FIRE command. The processing module is configured to generate an initiation signal upon receipt of the FIRE command. At least one of the power source and the processing module is disposed in the first housing, and the first housing has a first connector. The initiation unit has a second housing within which is disposed an initiation module that is configured to discharge initiation energy sufficient to initiate an explosive charge associated with the device. The initiation module is connected to, or connectable with, the processing module such that initiation module can receive an initiation signal from the processing module. The initiation unit also has a second connector that is configured to mate with the first connector, thereby connecting the first and second housings. The initiation module is configured to execute a sequence upon receipt of the initiation signal, the sequence resulting in discharge of initiation energy from the initiation unit.