Racing stripes? -[ HMM ]-

A striped brush.

 

More precisely, it's a sonic toothbrush replaceable head, whose stripes race side-to-side at roughly 250 hertz, or 15,000 oscillations per minute, to do its plaque-busting task. (For comparison, the electricity from your outlet alternates at 50 or 60 Hz, depending on your country.)

 

The stripes are not all show and no go. The dye in the dark blue pair of bristles fade with use, giving a visual indication the brush head needs replacing.

Done