For the aircraft engines which require high-density mounting, the seal must be very compact and light in weight, too. EKK has wide experience in the application of seals for aircraft services and has introduced the compact seals of the 700 series (the EKU750 and the EKU770) and the 800 series (the EBU800) in the market. The sizes of these seals are now regarded as the industry standards. Especially, the 800 series are the most precise and compact seals, utilizing a welded metal bellows as the secondary seal, and provides the world’s best rotating performance in high speed, high temperature and extremely low temperature conditions. The 800 series seal is used in the liquid oxygen service for the secondary propulsion engine and in the liquid hydrogen turbo-pump for the primary propulsion engine of the domestic rocket “H-II A”.