From MUZZY:

Our Zero Effect rest created a resurgence of drop-away arrow rest technology and has proven to be one of the best and most accurate rest on the market today. Now we are excited to introduce the Next Generation of the Zero Effect rest. The newly re-designed Zero Effect-Next Generation series comes in 3 new models:
At the beginning of the draw the Zero Effect Arrowrest is down and away from the arrow. As the arrow is drawn, the unique hook shape of the rest rises and "grabs" the arrow from any position on the shelf sliding it onto the "V" notch for release.
Approximately three quarters of the way through the draw the arrowrest makes contact. The arrow slides inthe the "V" and the rest begins to lift the arrow into a launch position. This happens smoothly and quietly and is driven by the action of the cables on the cable guard.
At full draw the arrow is in a normal pre-shoot position, but at the moment of release the Zero Effect Arrowrest drops down and away as the cable slide zips forward. The result is perfect arrow launch with no drag, no interference and no torque because the arrowrest isn't even in contact with the arrow