Definition: Found in hobby-grade RC vehicles, the receiver and the controller each contain a crystal that is set to a specific frequency band and channel. Sold with Ready-to-Run vehicles, you can also buy pairs of crystals independent of the RC vehicle.
Unlike toy-grade vehicles that come with one pre-set frequency, a crystal can be set with variable combinations to help reduce radio interference problems with other RCs in the area -- but the crystal for the receiver and controller of a single vehicle must use the same combination of band and channel.

