This hard drive from Silicon Power has room for 4 TB of data. This model has a 2.5" form factor, which apart from this model is commonly used in SSD drives.
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Silicon Power 4 TB External Portable Hard Drive Rugged Armor A60 Shockproof Water-Resistant 2.5 Inch USB 3.0 , Military Grade MIL-STD-810G & IPX4, for PC/Mac/Xbox One/Xbox 360/PS4/PS4 Pro/PS4, Black
Memory C
4TB Silicon Power Armor A60 Shockproof Portable Hard Drive - USB3.0 - Black/Green Edition
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