This head plug is also very effective for dressing. It can be installed in the hex hole of the cap bolt to improve the perfection and prevent rust. [Product Details] Plating finish; Pack of 10; For M6; A: 0.4 inches (10 mm), B: 0.2 inches (5 mm), C: 0.1 inches (3 mm), D: 0.1 inches (4.7 mm)