The wireless microphone shall be a professional transmitter for audio signals with switchable carrier frequencies; preprogrammed groups with up to 12 compatible channels. An infrared signal shall be used to synchronize the frequency between trans-mitter and receiver. The transmitter shall send a tone key (32.768 kHz) to provide improved opera-tion reliability and prevent switching noises. The capsule shall be muteable. It shall have an input attenuator switch (0, -10 dB), a timed backlit LCD showing frequency group and channel, battery strength and locked/unlocked status. Frequency and power locking capability shall be included. Technical Specifications Carrier Frequency: 518 - 865 MHz (available frequencies depend on applicable country regulations) RF Output Level: 10 - 30 mW (dependent on frequency version) Battery Life: at least 8 hours (with 2 AA alkaline batteries) Overall Dimensions (LxD): SLX2/SM58, SLX2/Beta58: 254 x 51 mm SLX2/SM86, SLX2/Beta87: 243 x 51 mm Net Weight: 252 - 295 g (without batteries) depending on capsule