The C4 series (L Type) resonators apply to the frequency range 24 to 60 MHz. They are fabricated on a lithium niobate (LiNaO3) substrate, producing resonators with ultra compact and superior stability due to the high electromechanical coupling coefficient of the material. They use the third overtone resonance, so that they can oscilate at high frequency. They include two loading capacitors inside and their package are chip type for surface mount. It contributes saving space and reducing mount cost.