another thing i really like about these racquets are the serial number system. i copied this off the website, but I really think this is a great system.
Donnay™ Serial Number System
Donnay™ is the only tennis racquet manufacturer to use a serial numbering system to identify every racquet. Using this system you can place an order with us, giving us your current racquets serial number, and receive an exact duplicate of your current racquet down to the gram and millimeter. This is only capable with Donnay's strict quality control standards.
that way... 6 month down the road when you want another one, you can still get the exact same one you are hitting with