What type of extension cord should I use for a retractable reel?

Use a rubber-jacketed cord like SJEOOW or SOOW — not cheap vinyl SPT or SJT cord that stiffens and cracks. Rubber stays flexible in cold weather and after thousands of wraps. Look for a high strand count (300+ per conductor) to handle constant bending. A 14/3 gauge (good for 15 amps) is ideal; swap out the reel’s original vinyl cord for a 50-foot length of 14/3 SJEOOW, costing about $40-60.