The IMP 50D from Newtrent is an excellent backup battery for my iPod Touch 4th gen 64gb It's well-built, solid construction, it's easy to use, charges quickly enough, it has excellent attachments for all devices. Customer service from Newtrent is the very best! I'm very pleased with their service. I can't say enough about how excellent their customer service is! They have spent many emails answering my questions and advising me on which battery would best suit my needs.  Shipping was lightning fast! The imp50D charges my iPod Touch three full charges on one battery charge!!  I would highly recommend their products to anyone needing a great backup battery at an affordable price!! These batteries a must for traveling or as a backup when an outlet isn't readily available. 5 stars!