This thin plastic mousepad made from materials by the company Microthin features the blueberry Apple logo printed in a manner to simulate the translucent plastic Apple used in the iMac line of computers at the time. This mousepad is blue to match the blueberry iMac. Other versions of this design were available in the other five iMac colors: tangerine, lime, strawberry, grape, and graphite.
This mousepad is round and measures 8.5 inches in diameter. It is printed with a MICROTHIN PRODUCTS logo and small text along the bottom curve (in Apple Garamond font): ©1999 Apple Computer, Inc. All rights reserved. L04108A
The bottom of the mousepad is covered in printed dots that provide traction to prevent slippage. The stickiness (tackiness) of the material is still viable after about 20 years and can be reactivated by rinsing any accumulated dust with water. However, the entire mousepad is beginning to show signs of yellowing.
Source: No official sources found, additional colors confirmed on eBay