My torsion spring broke. I went to my local big box home improvement store and they did not have discern able data regarding one spring to 2 spring conversions. Furthermore, they did not even have the replacement spring. I bought 2 springs that were close, in my opinion. Well, long story short, and a lot of repair work, I saw a list of recommended spring dealers. Dan at DDM Garage Doors was the closest. i emailed him. He asked me all the pertinent data about my door. He told me what i needed, shipped it out. I got it the next day. 2 hours later my door was going up and down better that ever!!!Do-it-your-selfer's: be safe and do a lot of research. but do not guess at the springs. Call Dan and Jean at DDM Garage Door. I wish i had before i bought the first 2 springs!!!!