Reddit reviews Powerextra 2 x Battery and Dual Charger Compatible with GoPro HERO (2018) GoPro HERO 7 Black GoPro HERO6 Black GoPro HERO5 Black (Compatible with Firmware v02.60, v02.51, v02.00, v01.57, v01.55, 1.60)
We found 1 Reddit comments about Powerextra 2 x Battery and Dual Charger Compatible with GoPro HERO (2018) GoPro HERO 7 Black GoPro HERO6 Black GoPro HERO5 Black (Compatible with Firmware v02.60, v02.51, v02.00, v01.57, v01.55, 1.60). Here are the top ones, ranked by their Reddit score.
Battery and charger are fully compatible with GoPro HERO 2018 GoPro HERO7 Black GoPro HERO6 Black and GoPro HERO5 Black.Each battery features 3.85v, 1500mAh high capacity, making your GoPro black last longer.Dual Battery Charger makes it convenient to charge two HERO6 or HERO5 Black batteries simultaneously.Compatible with firmware v02.51, v02.00, v01.57,v01.55 and future firmware update, NOT COMPATIBLE with the GoPro HERO5 Session, HERO4, or HERO3.Package includes 2 x Battery; 1 x Dual Battery Charger; 1 x USB Cord, 1 x Microfiber Cleaning Cloth.
Link to where you purchased the batteries please.
Edit: Found them here