O-Rings, also known as O-seals, toric joints or simply OR, are considered the most popular sealing solution and by far the most widely used type of seal due to its simple, versatile and cost-effective design. O-Rings are round loops generally made of elastomer (O-Rings can be made also in PTFE and other plastic materials) with a round shaped cross section, extremely easy to install and to maintain. O-Rings are primarily used as a static sealing element in radial and axial applications (flanges, end covers) to prevent any leakage or loss of fluid and in a variety of dynamic applications often in combination with back-up rings. O-Rings are available in a huge range of imperial (AS 568, BS 1806) and metric sizes (ISO 3601/DIN 3771, JIS B2401) and can be produced from a wide selection of elastomeric materials, including the most common NBR 70Sh, NBR 90Sh, FPM/FKM (Viton), FFKM (Kalrez), EPDM, VMQ (Silicone), CR (Neoprene), AU/EU (Polyurethane) and PTFE.