SanDisk 64GB Extreme PRO microSDXC UHS-I/U3 Class 10 Memory Card with Adapter, Speed Up to 95MB/s (SDSDQXP-064G-G46A) - Newegg.com
Amazon.com: 64GB Memory Card works with GoPro Hero 4 Black/Silver/Session - Sandisk Ultra 64G micro SDXC Micro SD Class 10 works with Hero4 Silver Edition / Hero4 Black Edition & Everything But