Premo-Flex Round Flat Cable Jumpers Molex Premo-Flex Round Flat Cable (RFCs) Jumpers are available in circuits ranging from 5 to 50 units and in lengths of 2', 4', 6', and 8'. RFCs provide an ideal electrical connection between PCBs and eliminate the need for connectors, thus enabling cost savings. Molex Premo-Flex Round Flat Cable Jumpers are suitable for various applications, including home appliances, cooling systems, mobile devices, computers, hand-held ultrasound and automotive applications.