My Bernina 440 QE came with the BSR, but I don't use it. My problem was coordinating the speed of the machine with the foot pedal with the speed of moving the fabric with my hands. This is much like playing the organ (hands on keys and feet on pedals) or drums (sticks, high hat and bass drum), and I don't do well with either. I discovered that if I set the variable speed where I am comfortable, I can either unplug the foot pedal and use the on/off button or press the foot pedal all the way down, and the speed doesn't change. Then, all I need to concentrate on is the speed of my hand movements.