Wasabi Power Extended Battery for HERO4, BTR-ABPAK401-BDOORS B&H
Amazon.com : Wasabi Power Extended Battery for GoPro HERO : Electronics
Buy Extended Battery Pack 4000mAh (Limefuel Epic L40GH) for GoPro HERO, External Mini USB Includes Extended Backdoor Housing up to 40 Meters, for entry-level camera only NOT COMPATIBLE with Hero 4, Hero
Extended battery "Extended Battery Pack" to make GoPro battery last three times longer than usual - GIGAZINE