Replaced the dead battery in an old iPod Nano I bought (really wanted a cheap Product Red one) and not even 2 days later the replacement battery expanded. I would call this
850 mAh Replacement Extended battery for iPod classic 5th 6th gen 30GB A1238 723905661663 | eBay
iPod Touch 2G Battery Replacement Kits & Services
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How to Replace Your iPod Battery - YouTube
iPod Nano 2G Battery Replacement Kits & Services
616-0404 800mah Touch 2 Battery For Ipod Touch 2 2nd Gen 2g Battery Replacement Battery 8gb 16gb 32gb +repair Tools - Mobile Phone Batteries - AliExpress
New 3.7V Li ion Battery Replacement 330mAh for iPod Nano 2 2G 2nd Gen MP3 with Tools|Mobile Phone Batteries| - AliExpress
iPod Touch 2 Battery Replacement – Geardo.uk
iPod Battery Depot | Replace your Battery Today
CELLONIC 616-0337,616-0311 Battery Replacement for Apple iPod nano 2 Gen. - A1199 / iPod nano 3 Gen. - A1236 MP3 / MP4 Music Player - 450mAh 3.6V - 3.7V Lithium Polymer: Amazon.co.uk: Electronics & Photo
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Internal Battery Pack for Apple iPod Nano 2
Battery for Apple iPod Classic 6th GEN A1238 80GB, 3.7V, 450mAh, Li-pl: Amazon.co.uk: Electronics & Photo