Finally a product that does exactly what it claims it does. Cancels noise, outstanding sound reproduction when listening to CDs, MP3s or on flight programing. Great for canceling out everyday distractions on the commuter train in and out of work too! Without any music input, they blissfully cancel out lifes disturbing noises too. Batteries and cost? - get real, you are buying a BOSE product - pony up your cash and enjoy your purchase. Batteries? You loose more small change in the sofa out of your sofa that what you will spend in buying AAA batteries. Remember, you only live once, and if you do it right, then it's all you need. ENJOY