I have a 15-91, I am the second owner. My great aunt bought it new around 1941 I believe. She had no children, and I was the only niece that really sews, so I inherited it. It was covered in yellow when I got it, so I had it hot-tanked and 'restored' (this was in the late 80's when I inherited it). I use it when I need to sew something heavier than I want to sew with my regular sewing machine. Although I have just acquired a Singer 111w151 industrial machine, so the 15-91 will probably be pretty much completely retired.