The ENG Kit from Sennheiser is a complete battery-powered wireless microphone system including a receiver and a plug-on transmitter. If you need more range, you can bump up the transmission power of the transmitters to 100mW. You can scan for available frequencies on the receiver and synchronize the frequency of the transmitter with infrared technology.
While the 2000 Series may visually resemble the Sennheiser Evolution Series, closer inspection reveals that the 2000 Series offers a lot more power and versatility. The 2000 Series is a diversity system that cleverly uses the output cable of the receiver as a second antenna. Diversity systems can really help you avoid drop outs and interference. The transmission power can be boosted, enabling you to receive audio from the transmitter from a great distance away.
The headphone output on the EK 2000 receiver is a handy way to monitor your signal, as well as have the system double as an IFB or remote listening device. There are charging contacts on the sides of the beltpack transmitter and receiver which will enable you to utilize the L 2015 charger and BA2015 rechargeable batteries (sold separately). The ENG Kit is a really powerful system for use on video cameras, in a field audio kit, or for any situation where you need to wirelessly transmit audio with ultra-compact components.