Floody - I tried several types and chose the DC 13X; I have had them in constant use for 2 years. They are very good in passive and active (especially in noisy piston twins), as well as having plenty of local warranty support. I can confirm the other reports of vastly improved radio comms and the ability to hear conversation-level speech in the cabin. The batteries are good for about 50hrs using new duracells rather than rechargables. I also carry a spare battery pack for those occasional in-flight failures. I wouldn't be without them - unless I could afford Bose.