Red Rollers ($135 per pair) are designed to filter RFI from interconnects. These heavy cylindrical objects are made of a fused ceramic material containing metal oxides. Placed around interconnects at both terminations, they filter RFI before it enters the next component. A similar product, Flat Rollers ($165 per pair), are machined flat on one side to fit components with closely spaced connectors. Red Rollers and Flat Rollers should be placed as close to the actual component as possible, as any exposed wire after the Rollers but before the component would become susceptible to RFI pickup.

 

 (The Red Rollers are, well, the red round things in the picture)