... -use computerized sock knitting machine 72-220 needle Cylinder :3.5, 3.75, 4 ,4.5, 5 inch knit various sock Richrui computerized sock ... knitting machine (3-3/4″ plain and terry Dual-use) 1,One main feed plus ... ,Possibility of 13 color plus ground or the same course.3,Drumless,fully electronic control system4,Exclusive inner cam block system ...