Most of the cases crystal of 11.059 MHz is used with 8051 series microcontrollers. The higher the crystal value, faster is the microcontroller speed. This also depends upon the requirement of the device connected across the microcontroller. In our RPM meter project, we used the same crystal. The particular value 11.059 is very important because when we used timers and counters, we make use of this value in calculations like Pulse Width Modulation and Timers etc. The crystals of such odd values are designed so that the all baud rates can be easily achieved.