Hopefully it works on the mt bike trail at night. so why did I give them only three stars? Because the quality of Haflingers is just not what it used to be. I was a bit skeptical but I CANNOT believe how cute and comfy these slippers are! It had great reviews and some buyers had even done side by side comparisons with other speakers that in was considering. (Update: An AT tech called me and he fixed the issue which was entirely my fault. I worked out in it and afterward I felt and saw a difference in my stomach! My usb cord stopped working after only 10-15 minutes & hasnt ever worked again. I expected at least a couple months of use but I feel like tossing them after a couple weeks. Ive washed them, threw them in the dryer with my clothes for about 5-10 minutes and the air dried. They seem durable and the contouring of the soul almost give them the comfort and feel of a walking shoe.