My battery died a long time ago when I was skying in France. It didn't like to be freeze (no way !)
I received the pack 3 weeks after placing my order (I live in Belgium, far far away US and China). I followed the instructions (I had difficulties to slide out the iPod of its casing, i had to force it a lot) and I succeeded.
My only regret is that the new battery is not more powerful. I agree to pay a little more to have a more powerful battery.
Follow the instruction, and go luck to slide out the iPod of its casing !