Microchip Technology OX-221 Oven Controlled Crystal Oscillators are standard high stability crystal oscillators that come in low-profile compact surface-mount packages. These oscillators make use of SC_CUT crystals that provide 10MHz, 20MHz, and 30.72MHz frequencies. The OX-221 oscillators are ideally suitable for applications such as base stations, test equipment, synthesizers, military communication equipment, and digital switching.