Available frequencies are (dependent on receiver) :

Frequency Guide:

Mini, Dual, & True Diversity Receiver: 902-928mhz - USA

Dual, & True Diversity Receiver: 823-832mhz - Germany, Austria, France, Greece, Finland, Hungary, Italy, The Netherlands, and many areas of Europe.

Mini, Dual, & True Diversity Receiver: 606-626mhz - UK, Australia, New Zealand, Taiwan.

Mini, Dual, & True Diversity Receiver: 863-865mhz - (License Free) Germany, Austria, Greece, Italy, The Netherlands.

For more information on which frequency to use in your area of the world look here: Frequencies for wireless microphones