The introduction of TNG RFID Tag is another toll payment method that does not impact the use of existing SmartTAG devices and Touch 'n Go card at all highway toll lanes.
Below are the articles that may be useful for you :
Can I still use the SmartTAG and Touch ‘n Go card at highways to pay my toll?
If I register and use TNG RFID Tag, can I request for auto-reload function as well?