The resulting ridged fields, which can be between 2.5 and 5 acres, are crisscrossed by canals and encircled by a moatlike protective ring. (discovermagazine.com)
For safety both Nuk baby toothbrushes feature a protective ring that prevents the brush being pushed too far into the mouth, the protective ring can also be used as a... (littleangels.ie)
There's also a cleaning brush with soft, bite - resistant rubber nubs, and a protective ring that fits on both brushes to prevent you from accidentally pushing it too far back in baby's mouth, which doubles as a brush stand when not in use. (whattoexpect.com)