This is the replacement for T5-210 simmerstat controls that are no longer available. The main difference is the shaft position. You will need to turn the control when you install it, so the knob will face the correct direction. Simmersat control used in many old style cooktops. All original with metal shaft. The size of the shaft is 3/4 Inches. The thin shaft is normally found in stoves over 20 years old.