AC WORKS 20 Amp 125-Volt NEMA 5-20P 3-Prong Industrial Heavy Duty Grade Male Plug AS520P - The Home Depot
What is the extra notch for on a 20-amp outlet? - Quora
Leviton 20 Amp Commercial Grade Double-Pole Single Outlet, Ivory R61-05821-0IS - The Home Depot
20A 240V Heavy Duty Single Receptacle White Color NEMA 6-20R Appliance/Air Conditioner Outlet (1) - Amazon.com
New WEBBER ELECTRONICS NEMA 6-20P RA Replacement Plug Right Angle Easy Assembly 20A/220V - Durable Nylon Construction - WB620RAP - 8 Possible Configurations - Amazon.com