SanDisk 4351501104 64GB Extreme MicroSDXC Card - Two Pack

The SanDisk 64GB Extreme MicroSDXC A2 two-pack is a performance-tier microSD solution targeting the throughput demands of 4K action camera recording and A2-class random access on Android smartphones. At 170MB/s rated read and 80MB/s rated write, these cards operate at the high end of the UHS-I performance envelope — fast enough to handle high-bitrate 4K video without dropped frames on compliant recording devices, and quick enough to make post-shoot card-to-computer transfers a non-event rather than a workflow bottleneck. The U3 Speed Class designation provides the meaningful guaranteed minimum: 30MB/s sustained write, which is the actual floor required for 4K recording reliability rather than the maximum burst figure.

The two-pack format with bundled micro card reader is pragmatic for action camera users who benefit from a dedicated spare — one card in the camera, one transferring to a workstation, with no gap in recording capability between sessions. Environmental durability ratings — waterproof, temperature-proof, shockproof, X-ray proof — are matched to the conditions of rugged outdoor use alongside waterproof cameras. The practical ceiling to plan around is the UHS-I bus limit: actual throughput is bounded by both the card's bus and the reader's USB implementation. For maximum transfer speed benefit, pair these cards with a UHS-I rated USB 3.0 reader capable of sustaining the full SDR104 bus speed — the bundled reader may or may not achieve that ceiling depending on its internal implementation.