Champion Power Equipment 20 ft. 30A 125/250V Fan-Style Flat Generator Extension Cord, L14-30P to Four 5-20R at Tractor Supply Co.
Iron Box NEMA 25ft 5-20 Extension Power Cord - Durable and Reliable 20A, 125V, UL Listed Portable Generator Cord for Transfer Switches, Data Centers, and Other High-Powered Applications (Black) - Electronics Power
AC WORKS 25ft NEMA 5-15P to NEMA 5-20R Cord 25-ft 10 / 3-Prong Indoor/Outdoor Soow Super Heavy Duty General Extension Cord in the Extension Cords department at Lowes.com
Laird SSPC20A-100 Stage Systems Heavy Duty 20-Amp 12/3 AC Power Extension Cord w/ Quad Box - 100 Foot
Southwire 50 ft. 10/3 STW 20-Amp Power Distribution Outdoor Heavy-Duty Generator Extension Cord with Power Light Plug 26188802 - The Home Depot
parkworld 6 ft. STW 12/3 20 Amp 125-Volt NEMA 5-20 Extension Cord 62190 - The Home Depot