these springs come in several lengths and strengths. in my old house, one of them broke (i'm glad no one was around). anyway, i made the mistake of replacing only the one side. being that the two springs were about 10 yrs in age apart and probably different manufacturers, the door rose cock-eyed causing binding problems. i went back and bought another spring corrected the problem. my point, i'd replace both springs at once. pay attention to the dimensions of the original spring, too, so you won't be guessing at the store.