Godox X1T-O Firmware v05 adds: To add the Fn-10 C.Fn custom setting so that the customer can set RF ID value. You can find the firmware update here or download it directly here. Godox X1T-O: B&H Photo / Amazon / Adorama Godox TT350O: B&H Photo / Amazon Godox AD200: B&H Photo / Amazon Godox AD600M: Amazon Godox TT685F: B&H Photo / Amazon Godox V860IIF: B&H Photo / Amazon