I was working on a very old well built Braun ventilation fan circa 1960’s. It was a very well made unit that only had a bad blower wheel. This blower wheel came up in my search. Due to the age of the unit, I thought that I would need to modify the part if I was able to get it to work at all. Based on the cost, it was worth the risk. I was very happily surprised when the part arrived and fit perfectly without any modifications.