Dimension belts are not always what they say. OEM belt cross overs may say 1/2-53 but the OEM belt may be slightly wider or narrower with a different cut angle, and the length may not be exact length either. Can cause problems in some cases. Had a john deere that I tried to put a dimensional belt on a few years ago and would only last about 15 minutes before it would get destroyed. Problem was the cross over belt was cut at an angle of 21 degrees but the JD belt was a 15 degree.