Direct swap with the original ballasts but you have to be careful. I originally bought bulbs thru home depot I believe they were Sylvania but they did not work. I read the box and they were only compatable with certain ballasts. It seems like Costcos are compatible with all. They worked with no problem. I read by changing the whole light with a led one it could be a lttle brighter but my fixtures would have been to hard to change.
