Samsung 64GB Flash USB Disk 3.0

3.0 Samsung USB Disk - Silver 64GB

About REAL Capacity

64GB  = approximately 54GB-62GB 

This is calculation difference between manufacturer and your PC, please Google 'Memory card capacity' to get more information.
For your reference 

Your PC says 1GB = 1.073741824 Billion bytes where Market Defines 1 GB = 1.00 Billion bytes.

Speed testing:

1) About USB Flash 3.0, please use a USB 3.0 card reader to connect a USB 3.0 interface for the H2testw on your PC. 

About USB Flash 3.1, please use a USB 3.1 card reader to connect a USB 3.1 interface for the H2testw on your PC.

If you use a USB 2.0 interface the speed will be much slower because:

The bandwidth of USB 2.0 is 480 Mb/s, whereas the bandwidth of USB 3.0 is 5 Gb/s.

2) Actual speed may vary depending on host device conditions (card reader, adapter, USB port etc.) Write speed will be slightly lower.

• Your PC says 1GB = 1.073741824 Billion bytes where Market Defines 1 GB = 1.00 Billion bytes
•  Backward compatibility to 2.0

About USB Flash 3.0, please use a USB 3.0 card reader to connect a USB 3.0 interface for the H2testw on your PC.

About USB Flash 3.1, please use a USB 3.1 card reader to connect a USB 3.1 interface for the H2testw on your PC.

If you use a USB 2.0 interface the speed will be much slower because:The bandwidth of USB 2.0 is 480 Mb/s, whereas the bandwidth of USB 3.0 is 5 Gb/s.

• 2) Actual speed may vary depending on host device conditions (card reader, adapter, USB port.