Amazon.com: 18-8 Stainless Steel Hex Nut, Black Oxide Finish, DIN 934, Metric, M4-0.7 Thread Size, 7 mm Width Across Flats, 3.2 mm Thick (Pack of 100) : Industrial & Scientific
Amazon.com : Uncle Bill's Sliver Gripper Tweezers Black Oxide Steel w/Keychain Clip (2-Pack) : Beauty & Personal Care
Black Oxide Coating: A Complete Guide to Precision Machined Finish