Commercial Grade C9 LED replacement bulbs are the top choice for high end Christmas lighting applications. With significantly better illumination than standard C9 LED stringer sets, your displays and perimeter lighting will take your Christmas and holiday lighting projects to the next level. These aren't your typical big box retail store bulbs, they are specifically made to hold up to the demands of high end Christmas lighting. C9 LED replacement/retrofit bulbs fit into standard intermediate, E17 base sockets.