Commander-PR, Is Not A Stand-Alone Unit, Must Be Used In Combination With Vocopro Commander-Play-4.
Frequency range: 3: 908.5-915.0 MHzFrequency range: 4: 921.5-928.0 MHzImpedance: 680 OhmPower: 3.7v Li-on 650mAh Rechargeable BatteryNot a stand-alone unit, must be used in combination with VocoPro COMMANDER