The rubber feet I use are from a cd rack I bought, they keep it from sliding on a slippery surface. When I first installed the FOP, it was very annoying as it would hit a certain resonnance that got very irritating, I could stop the noise by manipulating the fan (moving it slightly), but it would eventually start up again. I tried bending the clips to tighten the tension but it still rattled. The feet have worked great for the last 3 weeks.