Sigma Wire Extension Cords Sigma Wire Extension Cords RV aftermarket customers are raving about the durable, yet very flexible jacketing on our extension cords. These cords... are made to withstand the coldest of temperatures with ease of use. Part No. Length Description Male Female Cap/Connector Extension Cords 130 131 140 25' 50' 10' 25MF30A 50MF30A 10MF30A... Heavy-duty 30 Amp-125V extension cord. Flexible PVC jacketing allows for ease of use and flexibility during cold winter months. Made to 10/3 AWG specifications. 155 30' 30MF50A...