Thank you for viewing. I have been using this for about a week with the mx-ergo. To reduce shipping costs, I will disassemble the product's outer box for packaging. - Brand: perixx - Model Name: PERIPRO-303 - Diameter: 34 mm - Application: For trackball -Product Description- The "Black" version is now available in the PERIPRO-303 series!! The PERIPRO-303 GS is a glossy, elegant black replacement ball. Diameter 34 mm / Body weight approx. 25g. [Glossy Finish] The glossy finish of the ball allows for agile and smooth movement, increasing the sense of speed. It improves work efficiency and reduces the burden of mouse operation. It is suitable for gaming, large displays, and working with multiple monitors. [Rich Compatibility] The 34mm ball is compatible with PERIMICE-517, PERIMICE-717, Logitech, Sanwa Elecom, and Kensington M570 trackball mice. *Please note that the black color may not be compatible with Elecom trackball sensors. [Easy Removal] How to remove the PERIMICE-517/717 ball: Insert a round-tipped stick through the hole on the back of the mouse body and gently push to remove the ball. *Be careful as using a pointed stick or a hard brush may scratch the ball. Before use, wipe the ball with a soft cloth such as a glasses wipe to remove dust and excess oil, and then clean the inside of the mouse body with a soft brush or air duster before inserting. [Official Warranty] Manufacturer / Perixx Computer GmbH ・Designed in Germany ・If any defects occur during normal use, we will repair or replace it with a new one free of charge within the warranty period.