【New & Unused】Silicon Nitride (Si₃N₄) Precision G5 Ceramic Support Ball φ2mm Quantity: 2mm x 4 pieces (3 for replacement + 1 spare) Material: Silicon Nitride (Si₃N₄) Precision: G5 (High Precision Grade) Excellent high hardness and wear resistance, with a low coefficient of friction for smooth and light operation. Long lifespan, resistant to sweat and moisture, making it ideal for trackball customization and maintenance. The second image is a reference image of this support ball (2mm) being used in a Kensington Slimblade Pro that I use. ・Support ball sizes vary depending on the model. Please be sure to check the size that corresponds to your trackball. ・These are custom/maintenance parts. Replacement is at your own risk. Includes shipping, delivered via **Mercari anonymous delivery**.