Ariete fork oil seals, custom-made for your fork Ariete fork oil seals are different! The quality of their execution is matched by the unique nature of the material used: the carboxylated elastomer known as XNBR. This compound offers unique characteristics of resistance to abrasion, to high temperatures, and to the complex lubricants with numerous additives, which are used in modern forks as fitted to motorcycles and scooters. The reciprocating action of the fork tube against the seal subjects it to a notable degree of abrasion, which is complicated by the heat generated as a result of hydraulic displacement within the fork, plus the friction of the components involved. This mechanical wear and tear leads to accelerated ageing of the rubber which is also obliged to deal with the chemical action of the various additives in the lubricant. Oil seals are normally made from a nitrile rubber, known as NBR. This is used because it is cheap, and plentiful, not because NBR is the best material