ARI fork oil seals are made from a rubber compound specifically developed to work with the lubricants used in front forks, with all their various additives. This compound is completely different from that normally used for rotating shaft seals, since the physical environment inside a fork with its reciprocating movement, and the specialist lubricants, are completely different. We have designed ARI oil seals with a variety of lip profiles to make them longer lasting, while reducing to a minimum the friction effect against the moving shaft. Over the years, we have discovered the key role of a separating lubricant between the fork tube and the rubber of the oil seal to reduce to a minimum the surface friction, without affecting the function of the oil seal. After exhaustive testing, we have chosen a lubricant which is produced in the USA, and devised specifically as a rubber/metal lubricant for mechanical components used in the NASA space program. The advantage of this special grease, which we call ARISIL, is that it extends the life of the oil seal, and helps it retain its vital characteristics of flexibility and chemical resistance. For this reason, every set of ARI FORK OIL SEALS contains a single dose sachet of ARISIL, sufficient to lubricate the two oil seals supplied.