The light-tone single bag spring and the seven-zone induction bag spring are two different piano spring designs.

The light-tone single-pocket spring is a spring design used for light-music instruments (such as pianos). It consists of a small spring wrapped in a fabric bag that can be installed individually in each keyboard area. This design can effectively control the spring stiffness in each keyboard area, so that the entire keyboard can sound more evenly.

Seven-zone induction pocket springs are another spring design used in pianos. It consists of seven independent ammunition bags, each of which has a sensor that can sense the force of the strike. This design can make the piano sound more realistic because it can adjust the volume according to the strength of the strike.

In general, the light-toned single-bag spring and the seven-zone induction bag spring are both designed to improve the sound of the piano, but their principles and functions are different.