Reverse Stop & Lock Knob for Ultrafeed Sewing Machines is great for sewers who want precise and consistent stitch lengths in both forward and reverse. Set your forward stitch length and tighten the Lock Knob to lock the stitch length lever in place. Manually set the reverse stitch length with the Reverse Stop to ensure identical stitch length while sewing in reverse. Also use to set a consistent shorter reverse stitch for locking in your stitches. Easy to install on all Ultrafeed sewing machines.