No more saggy butt! This is a replacement spring grid that holds up the lower seat foam on any 1979-93 Mustang seat except 1979 Pace Car and 1982 GT Recarro. These usually rust out and break causing the lower seat foam to sag. This new spring is coated with plastic so there will be no rust problem. Note, this is called a spring even though it does not look like a typical helical spring. One per seat.