Grommet be used purely decoratively for crafting. When used in sailing and various other applications, they are called cringles. Sometimes field workers refer to them as grunyons. If metal or another hard material has a hole made in it, the hole will probably have sharp edges. Electrical wires, cord, rope, lacings, or other soft vulnerable material passing through the hole can become abraded or cut, or electrical insulation may break due to repeated flexing at the exit point. Rubber, plastic or plastic coated metal grommets are used to avoid this. The grommet could also protect the wiring/cabling from contamination from dirt,
Nilradical of a ring nilpotent ideal. As in the commutative case, when the ring is artinian, the Levitzki radical is nilpotent and so is the unique largest nilpotent ideal. Indeed, if the ring is merely noetherian, then the lower, upper, and Levitzki radical are nilpotent and coincide, allowing the nilradical of any noetherian ring to be defined as the unique largest (left, right, or two-sided) nilpotent ideal of the ring. Nilradical of a ring In algebra, the nilradical of a commutative ring is the ideal consisting of the nilpotent elements of the ring. In the non-commutative ring case the same definition does not always