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Speed Class | SD Association
SanDisk Extreme 32GB UHS Speed Class 3, V30, A1 MicroSDHC Memory Card (SDSQXAF-032G-GN6MN) for sale online | eBay
Amazon.com : SanDisk 128GB Extreme Pro Memory Card works with Canon EOS Rebel T5, T6, T6i, T7i, EOS 5D Mark IV, 6D Mark II, 5D Mark III, DSLR Camera SDXC 4K V30
A beginner's guide to memory cards: Digital Photography Review
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