Check that you have zig-zag springs (as shown). This will not work with broken seat springs, strap webbing, or coil spring construction (found in big man’s chairs).

You can install different thickness configurations depending on the severity of your sag. Stack 1, 2, or 3 pieces thick until you get the amount of support desired.

There is no need to cover or support the entire seat area, just place SagsAway in the center of the seat.