O-ring has the following advantages compared with other types of seals: one for the form of a variety of sealing: static seals, dynamic seals, suitable for various uses materials, dimensions and grooves have been standardized, strong interchangeability fit a variety of Exercise: rotary motion, axial reciprocating motion or a combination of movements (for example, rotating back and forth combined motion) 3 suitable for a variety of different sealing medium: oil, water, gas, chemical media or mixed media. Through the appropriate choice of rubber materials and the appropriate formula to achieve an effective seal for oil, water, air, gas and various chemical media. Wide temperature range (- 60 ℃ ~ + 220 ℃), fixed using pressure up 1500Kg/cm2 (with reinforcing ring and use). 4, simple design, compact structure, easy assembly and disassembly. O-ring cross section structure is extremely simple, and self-sealing, sealing performance and reliable. O-ring and install parts of the structure is extremely simple, and the formation of standardization, so are very easy to install replacement. Variety of materials. Can be selected depending on the fluid: nitrile rubber (NBR), Viton (FKM), silicone rubber (VMQ), B-propylene rubber (EPDM), chloroprene rubber (CR), butyl rubber (BU), poly tetrafluoroethylene (PTFE), low cost of natural rubber (NR) 6, 7, the dynamic frictional resistance is relatively small