https://us.community.samsung.com/t5/Tablets/Galaxy-Tab-S8-Ultra-microSD-compatibility/m-p/2259791#M27515 The max SD size tested is 1TB. Buy a card sold and shipped by Amazon.com. If the price is too good to be true it's probably fake. If you have a Windows pc then download H2testW and check every card you buy. If I was buying one for my Ultra I would get the SanDisk Extreme 512gb A2 card. <A href="https://www.amazon.com/SanDisk-Extreme-microSDXC-Memory-Adapter/dp/B07P7M6K35/ref=mp_s_a_1_5?crid=3III8P2VEQMYW&amp;keywords=512gb+micro+sd+card&amp;qid=1651319918&amp;sprefix=512gb+micro+sd+card%2Caps%2C90&amp;sr=8-5&amp;ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840" target="_blank">https://www.amazon.com/SanDisk-Extreme-microSDXC-Memory-Adapter/dp/B07P7M6K35/ref=mp_s_a_1_5?crid=3III8P2VEQMYW&amp;keywords=512gb+micro+sd+card&amp;qid=1651319918&amp;sprefix=512gb+micro+sd+card%2Caps%2C90&amp;sr=8-5&amp;ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840</A> Sat, 30 Apr 2022 12:02:03 GMT bill-e 2022-04-30T12:02:03Z