SanDisk 400GB Extreme MicroSDXC UHS-I Memory Card - Fast 4K Storage

Our review of the SanDisk 400GB Extreme MicroSDXC UHS-I card finds it best for photographers, action camera users and mobile gamers who need large, reliable storage with fast transfer and app performance. The single biggest reason to buy is the combination of high capacity and performance: up to 160MB/s read speeds and A2 rating for quicker app loading, which together make moving large 4K video files and running apps from the card noticeably smoother than with basic microSD cards.

Key Features

• High read speed: Up to 160MB/s read speeds reduce wait time when transferring high-resolution photos and 4K UHD video to a computer or compatible device.
• Fast write performance: Up to 90MB/s write speeds support burst shooting and fast video recording on compatible devices, helping avoid dropped frames during long takes.
• 4K and Full HD ready: UHS Speed Class 3 (U3) and Video Speed Class 30 (V30) make the card suitable for recording 4K UHD and Full HD content without sustained write bottlenecks.
• A2 app performance: The A2 rating indicates faster random read/write operations for loading apps and in-game assets when used in devices that support app storage on microSD.
• Large capacity: 400GB capacity provides ample room for high-resolution photos, lengthy 4K clips and large app libraries on phones, drones and action cameras.

Who It's For

The card is aimed at content creators and power users who shoot a lot of high-resolution images or record 4K video and need both capacity and speed. Photographers using burst modes, drone pilots capturing long 4K flights, and mobile users who keep many apps or games on removable storage will get clear benefits from the combination of fast reads, solid write performance and A2 rating.

Users who only need simple file backup or occasional Full HD photos and video might find lower-cost cards sufficient; also remember that the listed top speeds require compatible host devices to reach them, so an older phone or camera may not deliver the maximum performance.

Pros & Cons

Pros

• Very large 400GB capacity for extended shooting sessions and long 4K recordings.
• High read speeds up to 160MB/s that speed transfers to a PC with a compatible card reader.
• Write speeds up to 90MB/s and U3/V30 ratings that support reliable 4K and burst capture.
• A2 rating for better in-app performance when used as app storage on supported devices.

Cons

• Top read and write speeds depend on using compatible devices and card readers to realize full performance.
• Product does not include an adapter, so a separate adapter is needed for full-size SD slots.

Specifications

Capacity	400GB
Read Speed	Up to 160MB/s
Write Speed	Up to 90MB/s
Speed Classes	UHS-I, U3, V30, Class 10
App Performance	A2 rated
Format	microSDXC
Adapter Included	No adapter included

Our Verdict

The SanDisk 400GB Extreme MicroSDXC is a strong choice for creators who need roomy, fast removable storage for 4K video, burst photography and app-heavy mobile use; it delivers excellent transfer speeds and A2 responsiveness when paired with compatible devices, making it good value for power users who'll use the capacity and performance.

Frequently Asked Questions

Will this card record 4K video?
Yes. The card carries U3 and V30 ratings and supports 4K UHD recording on devices that accept microSDXC and meet camera write speed requirements.

Do I get a full-size SD adapter with the card?
No. This item does not include an adapter, so you will need a separate adapter or card reader for full-size SD slots.

Can I run apps from this card?
Yes. The A2 rating indicates improved random read/write performance for faster app loading when the host device supports running apps from external storage.