ISO 286-2 specifies dimensional tolerances for cold-drawn round steel, with precision classes from IT5 (tightest) to IT16 (loosest). For a 50 mm diameter bar, IT5 allows ±0.011 mm, IT7 ±0.025 mm, and IT9 ±0.063 mm. Cold drawing achieves tighter tolerances than hot rolling, making it suitable for precision parts like bearings and hydraulic cylinders. The tolerance class is chosen based on application: IT7 for general machining, IT5 for high-precision instruments. This standard ensures global consistency in manufacturing, reducing fit issues in international supply chains.