John,

It's called a "Straight Blade Inlet" 120 volt, 3 wire grounding male recessed receptacle. Be sure the one you get has a weather proof cover and is NOT of the "Twist Lok" variety. If you explain to the counter person what you are doing, they will fix you up. I'm pretty sure the one above is made by Leviton. GE, Hubbell and Daniel Woodhead also manufacture them, the last two being VERY expensive.

Grainger carries them, any marine store outlet (West Marine comes to mind [will be expensive]) or an electrical supply house can get them if they don't have them in stock. I don't think Lowes or Home Depot would have them, as it is not a "big mover" item.

If for some reason you can't find it there, I would be glad to get you one and ship it to you. I deal with most of the larger electrical manufacturers hear in the East.[X(]

Hope this helps.................