After one hour the speaker volume dropped way down to barely audible. Thought the battery was going, vibe still worked. When I got back to the car I noticed the two speaker slits were packed solid with dirt. When I got home I cleaned them out and the volume was good again. I covered the slits with heavy cloth, glued in place, hope it works. Poor speaker slit design, otherwise is good. Found only one wheat penny and a bunch of shotgun shells in the woods.