I have a regular singer needle in it size 16/100.. It has a flat edge on one side. the one that was in it when I couldn't get it to pull the bobbin thread up is round and has muva 100. At least that is what I think it has on it. Had look for a magnifine glass to see it.I was going to do a search on that to see what type of machine that goes to.
Thank you for the site on belts I will check it out.