Features:1. Black color, round shape, has a hardness of 50A.2. These silicone O-rings can be used in a wide temperature range from -22 °F (-30 °C) to 392 °F (200 °C).3. O-rings typically provide a pressure and fluid seal between cylindrically-shaped, overlapping covering surfaces and are commonly seen in flanges, valves, and various cylinders.4. This silicone o-ring has good resistance to ozone, weather, salt, oil transmission, non-petroleum brake fluid, fire-resistant hydraulic fluids, vegetable and animal oils, and high molecular weight of chlorinated aromatic hydrocarbons.5. Widely used for mechanical sealing, pressure, gas compressor, reaction, heat exchanger, boiler, filter, electrical appliance and other fields. Specification:Material: Rubber Case Color: Black Size Types: 24 Sizes (As the picture)Quantity: 1 Set (740pcs)Package Included:1 Set (740pcs) O Rings