"Upgrade" means using lower capacity flash memory upgrade to higher capacity flash by software.

For example, use 256MB can upgrade to any higher capacity as 512MB, 1GB, 2GB, 4GB, 8GB, 16GB or more. When customer buys the upgrade flash memory drive, the real capacity is the lower flash capacity.

For example, when customer buys a 1GB upgrade to 8GB flash drive, the real capacity is 1GB only. When customer plug the drive into their computer, they will see the disk shows 8GB. If they store the data more than the real capacity 1GB, the more part than 1GB will be stored in the disk of the computer. If they plug the drive into their computer again or into another computer, the data which more than 1GB will be lost.

The best way to try if your USB Flash Drive is a full capacity drive or not, you could store full capacity data which the drive shows, and then take it to another computer. If it lose some data, then it's an upgrade flash drive or a drive with not full capacity.