Is there some sort of thin pad to lock in the Roamio Basic?

I installed two Roamio Basic boxes in the final location. The surface of the table is very slick and the Roamio Basic boxes are extremely light and move very easily on this surface. Is there a thin pad I can use to kind of lock the boxes in place? I am worried that someone could bump into the table and the Roamio boxes would slide and cause damage to the HDDs inside them. I don't want to use double-sided tape or Velcro. I guess a large enough mouse pad might work, or even one of those things that you can put under a rug to keep it from sliding. Any other options being to consider? Thanks a lot for any help.