Juki TL2010Q Demo 9"Arm Straight Stitch Sewing Quilting Machine, Serviced , LED, SubTension, 1 Pedal Foot Control, Trim, Speed Control, 1500SPM, 7Feet

Sub Tension Unit Even if strongly twisted thread should be used, the unit will avoid "return of twist of thread" and supply needle thread to the main tension unit without thread quivering. It helps sewers create sttiches with stable thread tension.