The Petosan Silentpower Toothbrush Replacement Heads combine the benefits of a double headed toothbrush with Sonic Technology. The 45 degree angle of the brush heads allows you to reach both above and below the gum line. 20,000 Bristle Strokes per minute allow you to clean your pet's teeth quickly and more effectively than a manual brush. We recommend using different brush heads to avoid cross contamination if the brush will be used on more than one pet. For pets up to 34 lbs.