These O-Rings were made with Buna-nitrile, resists penetration and can save your job when working on a variety of projects such as faucets, high-pressure washers, and various other hardware and plumbing works. Features: Practical O-Ring, metric size, wide applications. Made with Buna-nitrile, a specially formulated material that resists penetration, large durability. Can save your job when working on a variety of projects such as faucets, high-pressure washers, and various other hardware and plumbing works. With 32 sizes available distributed across 419 O-rings, you're likely to find what you need in nearly every situation. Comes with a hard carrying case to make it easy to store and transport anytime. Specifications: Material: Buna-nitrile Size Type: Metric Sizes 3, 7, 10, and 13 by 1.5MM, 4.4 and 5 by 2MM, 10, 11, 13, 14, 16, 18, 19, 21, and 22 by 2.5MM, and 18, 20, 22, 23.5, 25, 26.5, 28, 30, 31, 33, 34.5, 36, 38, 41, 44, 47, and 50 by 3.5MM Total O-Ring: 419 Package Weight: 642g / 22.65ounces Package Size: 250 * 160 * 40mm / 9.84 * 6.3 * 1.57in Packing List: 419 * O-Rings 1 * Storage Box