A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to generate an electrical signal with a very precise frequency. Crystal oscillators are used in many electronic devices that require a precise and stable clock signal such as microcontrollers, radio transmitters and receivers , timing devices, and audio equipment.

This specific crystal is rated at 20MHz. The oscillator is housed in an HC-49/US package, compatible with breadboards and through hole perfboards.