BLACKLINE M6 B lackline black cap nuts DIN1587. These can be used in combination with the black lock screws but also fit other metric screws. High-quality black HCP coating: The unique coating with high corrosion protection (abbreviated HCP coating) is a deep black surface treatment with high corrosion resistance and low layer thickness. Due to the very limited layer thickness and integrated lubricant, the HCP coating is an ideal solution for our fasteners. The nuts continue to fit the screws and the screws continue to cut well into the wood. This unique black surface treatment results in corrosion resistance of over 500 hours without red rust in a salt spray test. Of course, the surface treatment is completely free from harmful substances such as toxic chrome VI and complies with European directives and RoHS. Note: These cap nuts are supplied in blister packs of 25.