Precision meets reliability with the SPI 21 mm Diameter Chrome Steel Gage Ball. Manufactured to Grade 25 Accuracy standards, this high-quality dimensional measurement tool is essential for calibration, layout, and machine setup applications. The chrome steel construction ensures durability and consistent performance in various measurement scenarios. With its precise 21 mm diameter, this gage ball provides reliable reference measurements for quality control processes and dimensional verification tasks. Part #14-831-2 from SPI's trusted line of measurement tools delivers the accuracy professionals demand for critical inspection work. This gage ball is an indispensable addition to any metrology lab or manufacturing facility where dimensional accuracy is paramount. Perfect for use with coordinate measuring machines, height gages, and other precision measurement equipment.