When taking classses at an area community college in Sacramento (back when sewing was offered), the classroom had some of these. We preferred not to use those machines at all, and if that was all that was available, we used the sewing machine only. We preferred the regular sergers. I remember them being on sale at those cheapo sales, TWO IN ONE SEWING MACHINE. MAKE PROM DRESSES, SWIMWEAR, EVEN DELICATE LINGERIE. This had to have been about 1990 or so.