Genuine Speed-Tec spare/option part. For Zenoah G230/G240/G260/G270/G290AN - expansion sealing gaskets are in use in the 2-stroke motor sports for years and are based on NBR-linked cellulose fibers. They are especially used for sealing hot oils, greases and fuels! The sealing material is compressed during assembly, and as soon as it comes into contact with fuel, it swells again. Thus it is i.e. possible to make up for irregularities in the sealed surfaces (i.e. cylinder / crankcase) and seal them properly! The material of the SPEED TEC AN - expansion sealing gaskets guarantees a very good dimensional accuracy and is often the solution for leaks on your engine! Technical data of the material in contact with fuel:- Rebound ASTM G > 30%; increase in thickness < 5%; weight gain < 55%;- Compressibility ASTM F36 G 22.5% +/- 2.5 27.5% +/- 7.5 The SPEED TEC AN - expansion sealing gaskets are available in the following versions:# ST-AN26V carburetor gasket 0,25/0,50 mm# ST-AN25I insulator gasket 0,25/0,50 mm# ST-AN24L air filter gasket 0,25/0,50 mm# ST-AN22 cylinder gasket, two bolt 0,25/0,50 mm# ST-AN42 cylinder gasket, four bolt 0,25/0,50 mm# ST-AN23G crank case gasket 0,25/0,50 mmContents:1 piece