Conntek 20601-040 40-Feet 10/4 30-Amp 125/250-volt 4-Prong L14-30 Transfer Switch Cord/Generator Extension Cord
40FT Heavy Duty Outdoor SJTW 10/4 Generator Extension Cord, 3 Pole, 4 Wire Grounding, NEMA L14-30P to NEMA L14-30R Max Power: 7500W, Stays flexible in cold weather, Heat Resistant up to 221F  Application: Transfer Switches, Generator etc.  Approval: Plug, Connector and SJTW: UL, C-UL. Limited one year warranty.