Everything is said in the title. The key does what it announces, I took in 64GB and it's very comfortable to transfer full seasons of series from my computer to my phone, for example, or to share with friends or colleagues without using a computer. I have associated with a small attachment carabiner clasp type of metal, for hanging in my keyring and disconnect the power quickly, it is very convenient.
The flow rates are average, even USB3. However, one can easily guess by seeing the key template (very small, wide as a USB tip). I recommend it.