COG is a popular dielectric for ceramic capacitors. It is a temperature compensating EIA Class 1 material. COG contains neodymium, samarium and other rare earth materials. COG ceramics have very stable characteristics. Capacitance change with temperature is approximately + or – 30 ppm/Deg C from -55 Deg C to 125 Deg C. Capacitance change with life is less than + or – 0.1%. Typically Q is more than 1000. There is little Q or capacitance change with frequency. Dielectric absorption is typically less than 0.6%.