The light Therapy Works but the controls are in an awkward location for back use. With the Belt on, it is impossible to set the controls because they are around the back side of my waist. I have used it with and without the extender and can't reach or see it. Now I put the belt on, set controls, lock so nothing stops it accidentally, then try to attach the controls to the belt which works somewhat better. Lying down, the lights go off while the timer is on while locked. It is hard to see is the lights are on without disturbing the belt. A "ding" would be helpful too know when the timer finishes; when I try to look, the controls are disturbed.
I just received this little beauty and am delighted to be exploring it's function. all i can say so far is that it feels good. i am looking forward to working with this.