Quartz crystal resonators are many orders of magnitude more stable than LC circuits and when used to control the frequency of the local oscillator offer adequate stability to keep a receiver in tune. However the resonant frequency of a crystal is determined by its dimensions and cannot be varied to tune the receiver to different frequencies. One solution is to employ many crystals, one for each frequency desired, and switch the correct one into the circuit. This "brute force" technique is practical when only a handful of frequencies are required, but quickly becomes costly and impractical in many applications. For example, the FM radio band in many countries supports 100 individual channel frequencies from about 88 MHz to 108 MHz; the ability to tune in each channel would require 100 crystals. Cable television can support even more frequencies or channels over a much wider band. A large number of crystals increases cost and requires greater space.