Complex sentence: The decocker models have no manual safety; instead, when the lever is lowered it only cams the firing pin into the slide and drops the hammer, when the lever is released it springs back to the normal position.
Split into simpler sentences: The decocker models have no manual safety; instead, when the lever is lowered it only cams the firing pin into the slide and drops the hammer. When the lever is released the firing pin springs back to the normal position.