Below example for how to check PID and VID for USB Flash Disk in windows 7:
1 Connect the USB device to your computer.
2 Right-click on my computer ,then Click Manage.
3 Expand Universal Serial Bus Controller.
4 Right-click on the USB Device listed, then click Properties.
5 Select the Details Tab and Select Hardware Ids from the drop-down list.
6 VID for this USB dsik is : 095 and PID is : 1642.
Each USB device attached to a USB host must have a unique Vendor ID (VID), Product ID (PID), and Serial String combination in order to function properly.
The Vendor ID is obtained from USB.org and requires a yearly fee to maintain.
Product IDs are assigned and maintained by the vendor who owns the VID. Product IDs are normally used to distinguish between different products under a single VID — this is at the discretion of the vendor. If a Silicon Labs USB device is used in a product, it is permissible for a company to use their own VID or a Silicon Labs VID. To use a Silicon Labs VID, you must be issued a custom PID directly from Silicon Labs. It is not allowed to use a random PID under the Silicon Labs VID, nor to use a PID assigned to a different company.
The Product String is a text string used to describe the product. This string will be displayed in Device Manager whenever the USB product is connected to the PC.
The Serial String is used to distinguish between multiple devices which have the same VID and PID. It is the responsibility of the product manufacturer to serialize their own USB devices, but it is possible for Silicon Labs to pre-program the VID and PID into CP210x USB devices and perform serialization.