Low density: lightweight, low inertia. Uniformity of parts. Capability to absorb shock and vibration as a result of elastic compliance. Ability to operate with minimum or no lubrication, due to inherent lubricity. The relatively low coefficient of friction. Corrosion-resistance; elimination of plating, or protective coatings. The quietness of operation. Tolerances are often less critical than for metal gears, due in…