These expansion boards expand the RF solutions 725 Series of LoRa remote control modules providing extra inputs or outputs. There are two, 4 channel expansion boards available depending on whether you require additional inputs or outputs:

725-IP - 725 Series - 4 Input Add-On Module (RS 125-8184)
725-OP - 725 Series - 4 Output Add-On Module (RS 125-8185)

These expansion boards are compatible with:

RF Solutions 725-TRX8-1K - 725 Series 1 Km DIN Rail Transceiver (RS 125-8182)
RF Solutions 725TRX8-16K - 725 Series 16 Km DIN Rail Transceiver (RS 125-8183)