From Gizmag ...
The system's front and rear shifters each consist of a single push-activated thumb paddle, which shifts the bike to a higher or lower gear depending on whether the user applies thumb pressure at an upward or downward angle. Two sealed hoses run from a cylinder in each shifter to a slave cylinder in the respective AG-E derailleur, carrying mineral oil that activates it to move the chain the desired number of clicks, in the desired direction.
Gear changes of up to three cogs are possible with one push, and the system will work with 8, 9 or 10-speed cassettes.
Acros claims that AG-E has much less friction than traditional mechanical setups, that incorporate steel cables sliding against the inside of housings, and stiffer return springs in the derailleurs. Because the whole thing is sealed and doesn't use cables that stretch over time, adjustments should also be relatively few and far between â€“ as long as air doesn't get into the lines. When it does need attention, as is the case with hydraulic brakes, it will presumably not be particularly user-serviceable.