SanDisk Ultra microSDXC 128GB Review: Read the Symbols, Then Discount the 140 MB/s

Red and grey SanDisk Ultra 128GB microSDXC card marked U1, Class 10 and A1, shown on its own without the adapter

Product image supplied by the brand

In this guide

THE SHORT VERSION

The SanDisk Ultra 128GB card carries three symbols, Class 10, U1 and A1, and each maps to a minimum set by the SD Association. Those minimums are the only performance SanDisk is obliged to deliver. The bigger number beside them, up to 140 MB/s, is a read figure measured under conditions most phones will not reproduce.

Australian buyers get the same part, model SDSQUAB-128G-GN6MA with an SD adapter. SanDisk's Australian page sends shoppers to a reseller rather than a cart. On 5 November 2026 Amazon Australia sold it for A$46.09 through Veloreo Pty Ltd, shipped by Amazon, and Officeworks listed the same part number at A$40.00 but marked it unavailable online.

Our verdict

A reasonable expansion card at A$46.09 on Amazon Australia, or A$40 when Officeworks has stock, provided you treat 140 MB/s as a read ceiling and Class 10 and U1 as the only write promise.

A good fit for: Adding room for photos, downloaded video, music and apps to an Android phone, tablet, Chromebook or Windows laptop with a microSD slot.
We would skip it if: You shoot 4K, own a camera or drone that asks for U3, V10 or V30, or expect writes anywhere near the read figure.

Reasons to consider it

Class 10, U1 and A1 marks that map to published SD Association minimums
SD adapter in the packet, so the card also fits a full-size SD slot
SanDisk 10-year limited warranty, on top of Australian Consumer Law rights against the seller

The compromises

The 140 MB/s claim covers reads only and needs a compatible reader such as SanDisk's own
SanDisk prints no write figure, only that writes are lower
No V-class mark, and the SD Association says a V10 device cannot count on a U1 card's write speed

What we have not verified: SanDisk publishes no write figure, so how fast the card records in a given phone or camera is left unstated. The Amazon offer belongs to a marketplace seller and was re-read on 5 November 2026; the seller, the price and Officeworks' online stock can all change, so check the Sold by line and the part number SDSQUAB-128G-GN6MA at checkout. Amazon's listing title calls the card Black, while the card in SanDisk's photos and Officeworks' specification is red and grey.

The things in this guide

A closer look at the products, who they may suit, and what to check before buying.

Sound for adding space to a phone or tablet

Ultra microSDXC UHS-I Card with Adapter · 128GB

A1 and 128GB suit how most devices use a card: app data, photos and downloaded media, with the read ceiling as a bonus when offloading through a fast reader. The adapter in the packet covers a laptop's full-size slot.

Before you buy: The guaranteed sequential write floor is 10 MB/s, so a camera or drone that asks for U3 or V30 needs a higher tier, and Amazon's A$46.09 offer comes from a marketplace seller rather than Amazon itself.

$46.09 at Amazon Australia (Veloreo Pty Ltd)

Price checked 5 November 2026. Retailer prices can change.

Class 10, U1 and A1: what each mark actually binds SanDisk to

The card face shows Class 10 and U1, and SanDisk rates it A1. The SD Association defines the first two as minimum sequential write speeds and states that Class 10, U1 and V10 all indicate the same 10 MB/s floor under its test conditions. The symbols differ by bus generation rather than by the number they guarantee. Officeworks' specification sheet repeats the same part number and a red-and-grey card, so the Australian retail stock is the same SKU SanDisk documents.

A1 is a different kind of promise. SanDisk's footnote puts it at 1,500 read IOPS and 500 write IOPS, and the SD Association describes the class as a minimum average of random 4KB operations per second plus a sustained sequential figure. Random small-block speed is what launching apps from the card depends on, which makes A1 the mark that matters most when the card lives inside a phone.

140 MB/s needs SanDisk's conditions, and it only describes reads

For the 64GB and 128GB capacities the headline is up to 140 MB/s, and the disclosure spells out the conditions: proprietary technology pushes past the 104 MB/s UHS-I bus limit, a compatible device able to reach that speed is required, and write speeds are lower. A phone's internal slot or a laptop's built-in reader is unlikely to be that device. SanDisk's Australian page lists no price of its own and directs buyers to resellers.

No write figure appears anywhere on SanDisk's pages, so the only write number a buyer can hold the company to is the 10 MB/s implied by Class 10 and U1. The gap between a 140 MB/s ceiling and a 10 MB/s floor is printed on the packet for anyone who reads the footnotes.

Dashcams, drones and 4K cameras need a mark this card lacks

The SD Association's Video Speed Classes run from V6 to V90 so that a recorder can demand a sustained write rate. This card carries no V mark. V10 names the same 10 MB/s floor as U1, but the Association's own note says a device built around one class symbol cannot count on that write speed from a card carrying another, even at the same number. A dashcam or camera whose manual asks for V10 or higher has nothing on this card to match.

SanDisk describes the card as suitable for Full HD video and adds that support varies by host device and file attributes. 4K capture and most action cameras and drones ask for U3 or V30, which belong to a different SanDisk tier at a higher price. Using this card for that job means relying on performance its specification never promised.

A$46.09 from a marketplace seller, A$40 when Officeworks has it

On 5 November 2026 Amazon Australia's buy box showed A$46.09 from Veloreo Pty Ltd, shipped from Amazon's warehouse, with five new offers starting at that price. Officeworks listed the identical part, SDSQUAB-128G-GN6MA with barcode 619659200558, at A$40.00 but could not sell it online that day. SanDisk Australia names no direct price. Inside the packet are the microSD card and an SD adapter for full-size slots; no USB reader is included.

SanDisk's 10-year limited warranty sits alongside the remedies Australian Consumer Law gives against the retailer for a faulty card, and Amazon's returns block notes that a defective item may still be entitled to a remedy after the return window. Keep the receipt and the part number, which is the string a warranty claim will ask for.

Skip it for recording, and for anyone buying the headline number

Skip this card if a camera, dashcam or drone lists U3, V10 or V30 as a requirement, or if you plan to record 4K. The guaranteed write floor is 10 MB/s, SanDisk publishes no higher write figure, and read speed does nothing for a recorder waiting on writes.

Look elsewhere too if the 140 MB/s figure is the reason for buying. It describes reads through a compatible reader, and a phone slot or built-in laptop reader may never approach it. For adding space to a phone, tablet or Chromebook, A1 and a price in the A$40s make it a defensible choice; confirm the seller and part number before paying.

How we put this together

Built from the product pages and listings below, without test scores or results we have not measured. Specifications and prices change, so check the original page for the exact model, current price, delivery, and returns.

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