Usually called frequency indicators, namely the contract by the user or product specification given resonator frequency is resonant frequency under specified load capacitance.
      Boxes of different sizes, and the vibration mode of the crystal resonator can be obtained with different frequency ranges. General availability of the crystal box size smaller minimum frequency is higher, see Table 1.

Crystal Box Model vibration mode frequency (MHz)
HC-49U AT baseband 1.8432-25
                     AT third-overtone 20-70
                     AT fifth overtone 50-150

HC-49S AT baseband 3.579-27
                     AT third-overtone 20-65
                     AT fifth overtone 50-150

SMD7050 AT baseband 6-33
                     AT third-overtone 33-100

  SMD5032 AT baseband 12-44
                     AT third-overtone 35-100

      Should give full consideration to the possibility of selecting products that can be achieved, beyond the possible scope, costs would increase drastically or become impossible, when the frequency of the crystal box close to the lower limit, should communicate with suppliers.

      Load resonance frequency fL
      Under specified conditions, the crystal element and a load capacitance connected in series or in parallel, the resistive impedance of the combination of the two frequencies of a frequency. Usually the frequency of said indicator, i.e. contract or product specification by the user is given resonant frequency, the resonant frequency of the load under the predetermined capacitance. Boxes of different sizes and crystal resonator vibration modes have different frequency ranges available . General availability of the crystal box size smaller minimum frequency is higher, see Table 1.