In the 1980–1983 period, Shimano introduced three groupsets with "AX" technology: Dura-Ace & 600 (high-end), and Adamas in the low-end. Features of these components include aerodynamic styling, centre-pull brakes, brake levers with concealed cables, and ergonomic pedals. By 1985 Shimano introduced innovation only at the highest quality level (Dura-Ace for road bikes and XT for mountain bikes), then trickled the technology down to lower product levels as it became proven and accepted. Innovations include index shifting (known as SIS, Shimano Index System introduced in 1984), freehubs, dual-pivot brakes, 8-9-10 speed drivetrains, and the integration of shifters and brake levers. Also, these components could only work properly when used with other Shimano components; for example, its rear derailleurs have to be used with the correct Shimano gear levers, cables, freehub, and cassette. SunTour tried to catch up, but by the end of the 1980s they had lost the technological and commercial battle, and Shimano had become the largest manufacturer of bicycle components in the world.