REPLACEMENT TRACKBALL - Designed for any trackball mice using 1.34 (34mm) trackball size; Such as from Perixx: PERIMICE-517, PERIMICE-717, PERIMICE-520, PERIMICE-720, Logitech: MX Ergo, M570, Cordless, Kensington: TrackMan Wheel (not include Trackman Marble), Elecom: M-XT3DRBK (EX-6), M-DT2URBK, EX-G/DEFT Sanwa: MA-WTB43BK | SMOOTH SURFACE - The surface is treated with a special coating to provide a precise and smooth tracking performance | ABSOLUTE SPHERICAL - A diameter of 2.17 inches; Provides fast movements and works perfectly for multiple screen control | HOW TO REMOVE THE TRACKBALL - The trackball from PERIMICE-517/717 can be easily removed from the bottom hole of the mouse, using the tip of your finger | GLOSSY GOLD: Glossy gold trackball color; Also available in glossy red, glossy blue, glossy, purple, glossy pink, glossy yellow, glossy silver, glossy gold, and glossy lavender