This is a Sensor Foot (Q) For Husqvarna Viking Group 7 Sewing Machines. Part # : 4131920-45 / 413192045 / 4125975-45 The Sensor Q Foot is used for embroidery and free motion sewing, quilting and embroidery on especially thick or spongy fabrics. Put on the Sensor Q Foot for free-motion Quilting with puffy battings, free-motion and built-in embroidery on fabric with batting, thick terrycloth towels, and when there is a build up of embroidery thread or couched decorative threads. Not for OPAL series. Fits Husqvarna Viking models : Designer 1, Designer 2, Diamond, Designer Ruby Royale, Designer Topaz 30, Designer Topaz 50, Opal 690Q, Sapphire 930, Sapphire 960Q