Use the comparison table above to choose the interface that best suits your operating requirements. DigiMode-4 is our most fully featured interface, providing Tx/Rx audio transfer, PTT control, CAT control and audio/PTT isolation. DigiMode-3 provides Tx/Rx audio transfer, built-in VOX PTT control and audio/PTT isolation where CAT control is not required. DigiMode-3 Micro is a compact and economical interface providing audio transfer and built-in VOX PTT control. Compatible with FT8, FT4, JS8Call, PSK31, JT65 and other popular digital modes.