Welcome. I believe most treadle belts are 72" long and 3/16" thick and are trimmed to size.
https://www.amazon.com/treadle-sewin...+machine+belts
https://www.ebay.com/b/singer-treadl.../bn_7024723911
There are some alternatives that can be used, also. I used airline tubing on one, just to see if it could sew. Some of the links are no longer valid, but some are at
Treadle belt??? and
Treadle belt alternative..... and probably many others.
Janey - Neat people never make the exciting discoveries I do.
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