General Applications O-Rings from Apple Rubber are available in a choice of seven basic materials each in a range of optional Durometer (Shore A) Hardnesses. Other materials available upon request. Buna-N: In the Buna-N family, you will find compounds which are ideally suited for oil resistant applications of all types. Ethylene-Propylene: In the Ethylene-Propylene family, you will find compounds that are used extensively for outdoor, weather resistant uses, water appliances. The first choice for low torque drive belts. Silicone: In the Silicone family, you will find compounds which are excellent as static seals in extreme temperature conditions. Cast Polyurethane: In the Cast Polyurethane family, you will find compounds which are used predominantly in high hydraulic pressure applications and situations where highly stressed parts are subject to wear. Neoprene®: In the Neoprene family, you will find compounds which are the superior sealing materials for the refrigeration industry featuring resistance to ammonia and Freon®. Fluorocarbon: In the Fluorocarbon family, you will find compounds which make-up the preferred seals for aircraft engines, automotive fuel handling systems and hard vacuum service. Fluorosilicone: In the Fluorosilicone family, you will find compounds which make-up seals that are unparalleled for aerospace fuel systems and auto fuel emission control systems. All materials are compounded under stringent quality control for uniformity of physical properties, and to meet or exceed Government, Military, Space Program, Automotive, F.D.A., Industrial and Commercial specifications.