2mm Loose Ceramic Balls Al2O3 Alumina Oxide Bearing Balls

I have a Kensington Expert Mouse Trackball that I use with mt computer. It originally came with three 2mm ruby bearings that the Large Trackball rides against. (Bearings). During cleaning, I managed to loose one of the 2mm ruby bearings. I have tried replacements made from glass, acrylic, and stainless steel, and they wear out (flat spots form). I decided I needed ssomething that had the same or greater hardness as the rubies that came with the Trackball. I purchased 2mm Alumina Oxide 2mm balls, which have a hardness of 9, similar to the rubies, and so far they are working perfect. The manufacturer of the trackball does not sell replacement ruby 2mm ball bearings, and a new trackball costs around $100 USD. The 2mm Alumina Oxide balls are not showing any signs of wear. This is a good alternative if you should loose one of the OEM ruby ball bearings.

Our Photo lithography system has three metal flags with a 2mm ball in the end of each. The flags are used to define a precise reference distance between two surfaces. The balls are glued in and fell out of one of our flags. Replacement cost $450+ and several weeks of down time. I ordered 20 2mm balls and repaired the flags.