It was very easy to find the needed part on the website. It was packaged well and arrived quickly. Perfect!
Belt 4l580 - fs450, bh4000, bw5002, bw55
Belt 4l580 - fs450, bh4000, bw5002, bw5001, bw5502 mb10. about 54"
Buy this part and as many parts as you like and pay only $9.99 shipping, within the Contiguous United States.