We stock both crystals and resonators both widely used as clock sources for Micro-Controllers. The type you choose will depend upon your application. Crystals are far more accurate than resonators but they will require additional capacitors. Resonators come with internal capacitors and have better ESD, shock and vibration tolerance. Many of the newer Micro-Controllers now come complete with an internal basic clock which will need calibrating. Please check your Micro-Controller datasheet for your preferred option.