The sensor is on the lampost. The bulbs use the smaller screw in plug called Candelabra bulbs, then you must decide if you want to save money on the bulbs and replace them every year or two, then get the incadescent bulbs. They're cheap, maybe a $1 a piece or less.
However, if you're like most of us, you want to only change the bulbs every five to seven years and you want to use much less electricity, then buy the LED bulbs. I used to use the curly LED bulbs and they were much brighter, but they've been done away with and now this is about all you can find. Go to Lowes, Home Depot, Walmart or order from Amazon.
