Our Series 4000 O-Rings for ORB (O-Ring Boss) adapters are crafted from high-quality Buna-N Nitrile (NBR) material with a 90-Durometer hardness, ensuring reliable, long-lasting seals in hydraulic and pneumatic applications. These O-rings are specifically designed for use with ORB fittings, providing a secure, leak-free connection by compressing the O-ring into the machined surface of the fitting. The 90-Durometer NBR material is highly resistant to oils, fuels, and other chemicals, offering excellent performance in a wide range of industrial environments. These O-rings help prevent leaks, enhance system efficiency, and maintain the integrity of fluid power systems.