Our Air Conditioner was making a shrill buzzing noise. After researching what it could be, I learned it was the Contactor going out. Of the Air Conditioner brands this part was supposed to work for on this site, my AC brand, RUUD, was not on the list. However the part number matched both sets of numbers on my part, and the specs, so I ordered it. I used expedited shipping and it arrived in 3 days. I installed the part the day it arrived after double checking that the numbers matched my current part. Once installed, the loud buzzing completely stopped. Huge difference and much less expensive than waiting for my AC repair person to show up 3 weeks later to fix. Just be sure to take a picture of your current wiring, before you remove, and always check to be sure your power is off before starting any project that includes electricity.