When sourcing a 3 jaw chuck, you must prioritize clamping precision (runout), which for high-quality manual chucks should be within 0.05mm to 0.08mm. Consider the body material: High-strength cast iron (HT300) is standard for general use, while forged steel bodies are essential for high-speed applications to prevent centrifugal breakage. Additionally, verify the mounting type, such as short taper (Direct Mount) or cylindrical center (Backplate Mount), to ensure compatibility with your lathe spindle.