I use the Samsung Electronics 64GB Pro microSDXC Extreme Speed (UHS-1), and it works great.
http://www.amazon.com/gp/product/B009SK ... UTF8&psc=1
Also from the GoPro Website:
Not all Class 10 microSD cards have the same data write speeds. If you plan to shoot in 4k, 2.7k, or Protune video modes with your HERO3: Black Edition or HERO3+ Black Edition camera, we recommend using one of the following microSD cards for the best performance:
SanDisk Extreme 32GB microSDHC (SDSDQXL-032G)
SanDisk Extreme 64GB microSDXC (SDSDQXL-064G)
Lexar 32GB SDHC 633x (LSDMI32GBBNL633R)
Lexar 64GB SDXC 633x (LSDMI64GBBNL633R)
Lexar 32GB SDHC 600x (LSDMI32GBSBNA600R)
Lexar 64GB SDXC 600x (LSDMI64GBSBNA600R)
Delkin 32GB SDHC (DDMICROSDPRO2-32GB)
Delkin 64GB SDXC (DDMICROSDPRO264GB)
http://www.amazon.com/gp/product/B009SK ... UTF8&psc=1
Also from the GoPro Website:
Not all Class 10 microSD cards have the same data write speeds. If you plan to shoot in 4k, 2.7k, or Protune video modes with your HERO3: Black Edition or HERO3+ Black Edition camera, we recommend using one of the following microSD cards for the best performance:
SanDisk Extreme 32GB microSDHC (SDSDQXL-032G)
SanDisk Extreme 64GB microSDXC (SDSDQXL-064G)
Lexar 32GB SDHC 633x (LSDMI32GBBNL633R)
Lexar 64GB SDXC 633x (LSDMI64GBBNL633R)
Lexar 32GB SDHC 600x (LSDMI32GBSBNA600R)
Lexar 64GB SDXC 600x (LSDMI64GBSBNA600R)
Delkin 32GB SDHC (DDMICROSDPRO2-32GB)
Delkin 64GB SDXC (DDMICROSDPRO264GB)