yarn guide arm 43 comprises a lower yarn eye i e inner yarn eye 431a a recessed portion 430 on the surface of the lower yarn eye 431a a higher yarn eye i e outer yarn eye 431 and a screw 432 the support holder 49 has a cross shaped recessed portion 491 provided on the top surface and a hole 492 provided on the center of the recessed portion 491 the width of each of the intersected surfaces of the portion 491 corresponds to the width of the yarn guide arm 43 as such it is possible of mounting the yarn guide arm 43 from the front left or right side of the support holder 49 for user selection as to mounting the screw 432 is placed through the recessed portion 430 to the hole 492 for holding the yarn guide arm 43 and the support holder 49 together as to a short fabric yarn knitting the yarn path is from a yarn y through the inner yarn eye 431a the yarn brake 44 the tip portion of the incoming yarn tension detecting arm 45 the yarn eye 46 the yarn supply drum 47 the first pull off eye 51 and the second pull off eye 52 to a circular knitting machine and needles not shown as to a long fabric yarn knitting the yarn path.