I bought one of these and returned it a couple days later (from an electronics store - much more expensive than @ Amazon). While it had many qualities I was looking for, like the thick, protected connector for the ipod instead of a dangling wire, this unit just didn't do a good job of holding a charge. I followed all the instructions, charge it overnight, etc. but still it would only give and extra hour or so battery life to my 40 gig ipod. As tempting as this one is, I'd say pass and find one with proven ability to hold a charge.