One of the more important elements of all 3 models is that they use KLEER wireless technology to transmit uncompressed digital audio and control data. KLEER is similar to Bluetooth, but offers greater wireless range, better audio quality, and does not require pairing. With typical Bluetooth wireless headphones, you have to go through a pairing process to get the transmitter and headphones to "talk" to each other, which can take a few attempts and be quite frustrating. KLEER headphones are plug-and-play. This was my first experience with KLEER headphones and it was terrific. Audio quality couldn't have been better; I never experienced a bit of interference or distortion. I didn't test the wireless distance, but with advertised ranges of 60, 260, and 320 feet, you should have plenty of room to wander. The maximum range of Bluetooth headphones is 30 feet, so these Sennheiser models offer anywhere from double to ten times the wireless range. Pretty impressive stuff. As far as wireless control of the various volume, bass boost, and other controls offered by the headphones, they all worked extremely well. If I clicked, the button responded appropriately without the need to click multiple times in order for a function to engage.
