the introduce for 668SF as following:

This machine has such functions as automatic changing four colors yarns,automatic controlling tensions, automatic opening/closure switch for lifting cam, automatic widening, automatic expanding (while widening), automatic shortening, automatic changing knitting speed, automatic moving bed (0.5 - 1stitches), automatic batching-up, automatic stopping knitting for coarse knotsand ending out, automatic counting to stop knitting, power-off protection

Six (1 - 6) kinds of speed can be selected depending on different knitting materials and knitting width. The frame head can reverse at lower speed automatically while converting so theimpulsive force is slowed down in order to make the machine smoothly run .